RPR's pool is okay, and it has a nice splash area, but it's nothing special. SF has a much larger pool with a slide.
RPR is closer to the parks along the walking trail. SF is a bit further from the parks, though still walkable, and closer to Cabana Bay. Because pool hopping is officially allowed, going over from SF to the Cabana Bay lazy river is something to consider. I have not personally used them, but I hear SF has fire pits like Cabana Bay, and I know RPR does not. It's a small thing, but we like to do s'mores at least once a trip.
Usually when I stay at RPR it's specifically because I want the express passes. If I didn't care about EP, I'd probably prefer the amenities of SF.