personally i like martins but for more ratties go RUUD or FN 2 story. But personally i would go with the R-695 out of the 2 you said.
Eh you wouldn't have to get a double FN. A single-story FN would be fine for 5 rats, especially females. I'd just be careful and make sure they couldn't squeeze through, or modify it with hardware cloth just in case. Yeah, it's a pain in the butt to do so, but it is such an easy cage to clean and decorate. That's one reason why I chose it over a Martins.