I'll jump in first.  I've only had experiences with female rats (although am looking into adopting a pair of intact males).

for the most part they're ALWAYS on the go!  One little girl is content to sit on my shoulder and chew my sweatshirt, but the other... there's no stopping her.  she's crazy for new things to explore.
They really dont smell at all, all three are litter trained and one even pees there reliably.  Other than that, none of them mark outside the cage and i've had no problems.
All three girls love each other and love other pets (many may not agree with us doing this, but we allow quarantined hamsters (3) play with them and have had nothing but good times), and certainly love meeting new people to climb all over.
I think the girls best trait is their outgoing nature and their fantastic clean-fur smell, plus their willingness to play tag with me when i'm hyper and no one will go run. 
the worst... well, many times i would give anything to just sit in front of the TV and chill with the girls, and it gets frustrating when they want to keep going and going and going.  i have yet to tire all of them out at once.
for cutest, im gonna go with stealing things.  i love it, its so adorable.  but then again, others may not agree... haha
i dont think there's anything out-of-the-ordinary with girls, it seems to me that most of the 'unknowns' come with boys.  (buck grease, plugs etc)

i dont have an opinion on the neutering debate yet.  i believe that i would prefer to have males neutered, but this thread may very well change my mind/educate me further on the choice, which is fantastic.

so lets get this thread going!  i love me my edu-ma-cation. 

I've had only males until about mid-January.  I think I still prefer the boys.

Personality: Each one has had such completely different personalities.  I had Hunter who was very aggressive and only liked me and no one else of any species.  He was completely fearless and comfortable being anywhere or doing anything.  I had Cheech and Chupe, they had a father/son relationship.  Cheech raised and took care of the other one.  He was the most loyal thing I'd ever seen.  Chupe was all baby.  He remained innocent and friendly with everything he ever met all his life.  Nitro's aggressive toward other males, but super friendly with people.  He's a very confident and independant type.  Ethan's also very independant and confident, but laid back.  Nothing seems to bother him.  Last of the guys us Rupert.  He's always on the move and doesn't seem to have time for cuddling.  He's a little bit skittish, but mostly because he's aware of everything.  As far as the girls go, Creepers McNugget was VERY hyper efore she ended up sick and drained of most of her energy.  She loved everything and had that certain innocence.  Lizzie's playful and collects everything and puts it in her nest, but she'll also cuddle and stay on my shoulder if I'm busy.

Energy:, I'm going to go ahead and say the girls have been much more active, but not into as much.  The guys seem to get into all the trouble.  They seem to be the bigger chewers of mine too.  

Smell:  All of mine have been very clean and have had a pleasant smell.  I've never had a problem there.  The guys seem to mark a lot more, but even then, it's not overboard.

Sociability:  I can't say.  Cheech and Chupie were both very social and you could just put a new rat into their cage without any introductions and they wouldn't care.  Hunter was the meanest rat I'd ever want to meet and Nitro became aggressive with time until he tore a nasty hole into his former cagemate's belly.  His cagemate was the most docile thing in the world and had no problem letting him call the shots, but he tore into him anyway.  I haven't made any introductions with Lizzie yet, but she seems incredibly social.

Best Trait:  For the most part, the boys have been excellent shoulder rats.  I've been able to take them places and do things with them on me without having to worry about them suddenly becoming scared or anything.  Lizzie is the best behaved rat I've ever met.  If you tell her no, she stops.  If you call her, she comes no matter what she was doing.  If she starts to go somewhere and you don't want her to, you just tell her and she won't go near that area again.  She's very impressive.

Worst Trait: When the guys fight, things can get pretty nasty and if I separated them at first sign of bloodshed, even my closest two wouldn't have lived together and they couldn't live without each other.

Cutest Trait: I like when they open my mouth to see if anything tasty is in there, to lick my teeth, or just try to climb in.  Most of the guys and both girls have done this.  

Favorite Activity/Treat: All the guys have gone nuts over whipped cream.  I always keep a can of it around just for them.  The girls seem to like anything with a bit of a bubblegum taste.

Little Known Facts For Beginners:  I have to think about it.

To Neuter or Not to Neuter:  I know a lot of people swear by it, but I'm actually not a fan of neutering.  In all honesty, Nitro might have been able to continue to live with Cheech and Chupe, had I had him neutered.  I really don't know, because I didn't do it.  I just feel like it's altering who he naturally is and I don't feel comfortable doing that.

I think once boys get older, they sometimes have trouble cleaning "down there" and can develop a plug that their owner has to remove (the joy of having boys).

Thank you for asking Tattooed.
Does "down there" refer to a butt, or genitals?

*added by Edit*
I searched and found. Is it something visible, or how do you know you have to clean it?

I've actually had experience with this with two of my boys.  I'd never heard about it before.  Hunter was having a hard time urinating and when he would finally go, little bits of something could be seen.  One day I picked him up after he had been trying to pee.  I actually decided to look and see if there was something blocking it and his penis looked kind of funny.  Trying to do whatever I could for him, I rubbed just above it, to give him a bit of an erection, so I could see better.  There was all this waxy stuff inside, so I removed it, (you use your fingers and carefully take off the waxy build up), and he just peed all over the place.  I had to check him a couple times a day until he passed away.  This was very dangerous for me, as Hunter was the meanest rat in existance, and when he was uncomfortable, he was worse.  By the time Cheech got them, I already knew what I was dealing with, and was able to just take care of it.

1) Personality:

My girls are always on the move. I compare them to toddlers with short attention spans. I can't keep them focused on one thing for too long, as they're looking for the next thing to explore. My girls are ultra curious and are always looking for things to get into. Smeegol I find is just as curious, but not as long as the girls. Where as the girls are ALWAYS on the move, Smeegol doesn't mind stopping for a cuddle session every few minutes. I don't find their personalities to be very different. Both genders are really sweet.

2) Energy levels

Well like I said above, the girls are always on the move. They're really full of energy. Smeegol is full of energy, but only in little bursts.

3) Smell

I don't think either stink. But Smeegol definately has a stronger smell. I can't really describe it...Lol.

4) sociability

I've only had girls in groups of two or more. So I can't speak so much for the boys. But the girls are really sweet to eachother. I took the normal introductory procedures, and it went nicely. Haven't introduced Smeegol yet, so I can't really say.

5) Best trait

For the girls, definately their curiousity. I love how they like to explore everything.
For Smeegol, I love how he is willing to cuddle with me. Nothing better than watching a movie with a snuggly ratty.

6) Worst trait

For the girls, their determination and persistence! Gee. Playtime with the girls is a nightmare when I'm trying to keep them from going somewhere. No matter how hard I try they will always find a way, or will keep trying to push my buttons.

I'm not sure about Smeegol, haven't noticed anything yet...

7) cutest trait

Licking my fingers! Love ratty kisses.

8 )Favorite activity/treat

My girls and guys like whatever I give them.

10) to neuter or not to neuter

I'm neutering Smeegol just so he can go in with the girls. If I had lots of money I would definately get the girls spayed.

really?  i personally disagree, since i really want to create a space about how to care specifically for boys and girls.  but this is an awesome spot too.   

My friend wrote a very accurate and humorous assessment of boys vs. girls that you can read at her web site: http://www.furrattery.com/boygirl.html

Anyhow, these are my observations to your questions:

1) Personality
Depends on the individual rattie not the sex actually.


2) Energy levels
My girls are always on the move...always. If they aren't moving they are sleeping.

3) Smell
Boys have a definite stronger odor to their wastes. But its not bad enough to put me off the boys entirely. They do have a pleasant body odor that smells reminiscent of corn chips to me.

4) sociability
Girls generally are easier to integrate in large groups with each other than boys. There are exceptions to this rule however.

5) Best trait
Girls: Fun to watch, very entertaining, just busy, busy, busy little bees.
Boys: Like to snuggle, will settle down and watch TV or take a nap with you

6) Worst trait
Girls: If you want a pet that will sit with you or stay by your side, that's not usually not the girl's forte. They'd rather be off exploring.
Boys: Can be aggressive and territorial towards other rats once they reach maturity, even rats they've grown up. with.

7) cutest trait
Girls: Watching them build nests/hide stashes and try to carry items for stashing or nest building which are far to large for them...always at a dead run.

Boys: Waddling when they walk.

Cool Favorite activity/treat

My girls *love* pea fishing. They love it so much that any time they see any liquid at all outside their cage they gotta check it for peas! I have to watch they don't tip over glasses of juice or some other beverage intended for me sitting out while they are running around. Its hilarious!

My boys seem to like slowly roaming the room looking for good places to scent mark and finding where the females have been before. That and eating. They love to eat! Oh and scritches. My boys love scitches.
 
9) little-known-facts for beginners (like boys and their plugs  Blue Dumbo Smile)
None really here since I'm a noob myself...just watch your boys for aggression. They can sometimes fight to the death in a closed cage when theres no way for the losing rat to run away.

I had a really scary experience with three young boys I was rat sitting for a friend. One morning I found one of them almost dead in a pool of his on blood. I rushed him to the vet and fortunately he lived, but he was traumatized ever since then and has not been able to be with other rats ever since.

10) to neuter or not to neuter
It's all a matter of personal preference. Neutering will make a male rat more docile. But it's expensive and not beneficial health wise the way spaying is. I'd rather save my money for surgeries that are necessary.

Sometimes aggression issues can be worked out just by finding appropriate cage mates. 2 of my male rats absolutely hate each other, yet they get along fine with all the other rats. So rather than neuter the two and force them to live together, I just got another cage and have 2 boys in one. 2 in the other.

I have only ever had females so I am biased :p But my experience with females:

1) Personality: Well personality is different for every rat no matter the gender. Some may be mellow, some may be high strung, nervous etc and that is not gender specific.
2) Energy levels: Well when my girls want to play they are very hyper but all four of them love to just sit and snuggle most of the time.
3) Smell: I clean their cage once a week, I have them on aspen and sometimes on fleece. They only smell if I miss a cage cleaning. Little odour basically.
4) sociability: Again depends on the individual rat but my girls are very social with each other and with me and other humans. As I type Maggie is on my shoulder bruxing away.
5) Best trait: Ummm...the fact that they can be hyper for a little bit and then snuggly later on.
6) Worst trait: They tend not to get very squishy although my girls are rather squishy for females *squishes Jazz*
7) cutest trait: Their tails, their ears, their nose, their whiskers, they feetsies, their fur, their tounges or heck all of them. Girls don't really have gender specific body parts hanging around :p
Favorite activity/treat: Sitting on my shoulder and eating.
9) little-known-facts for beginners: I guess the thing that I didn't really know was that rats could need the vet so much. I have been lucky so far though.
10) to neuter or not to neuter: Typically it is better to spay it decreases the chance of tumours. I don't have my girls spayed though :/

Only girls until Veni gets here, but I'll go for it

1) Personality:

Each girl has her VERY own personality.

2) Energy levels

They're like maniacs on a crazy spree

3) Smell

Delicious! We keep a candle warmer on 24/7 and scent spray ('cause Delilah, our cat, has a sensative tummy and her poo smells like a city sewer system)
so we never have noticed a smell.

4) sociability

The three oldest girls don't like to cuddle but with one another and boy is it cutesy! Reba is a definate CUDDLE MONKEY! She snuggles in a fold in my shirt and falls asleep with me petting behind her lil' ears.

5) Best trait

EVERYTHING! Ratties are awesome, no matter the sex. I could name good traits of all the girls individually, but I'd find it difficult to that they all have the exact same best trait.

6) Worst trait

I have only one complaint. Kishi likes to bite my butt when we're playing on the couch. It isn't pleasant. lol

7) cutest trait

When they're all cuddled up together, I think. Or scaling the cage. I don't know, I could make a list!

 Favorite activity/treat

They LOVE bananas. They go just banana sandwhich for bananas.

9) little-known-facts for beginners (like boys and their plugs)

No matter that they're girls. They enjoying marking me ALL THE TIME. I'm having a LOT of difficulty litter training them and... they love to pee on me.

10) to neuter or not to neuter

I personally wouldn't spay or neuter any animal unless it improved their quality of life. For example, a male rat that is having so much agression that he is absolutely unable to live with other ratties, I'd have him neutered in hopes that the agression would go down and he'd be able to have friends, or if I was going to adopt an unwanted cat that was going to be put down, and I already had a female, then one of the two would have to get fixed to prevent more kitty babies.