Doesn't the 360 actually have more RPGs than the PS3?
"More" doesn't mean "better". The 360 and PS3 are fairly evenly matched on "good" RPGs at the moment, with the 360 having the Fable series and the PS3 having Valkyria Chronicles. The PS3's also had (and will have) improved ports of many of the 360 RPGs, such as Eternal Sonata; Tales of Vesperia; and Star Ocean 4. The PS3 also has access to older RPGs via PSN download and (if you have an old model PS3) PS2/PS1 backwards compatibility. Like I said, the PS3's getting there on RPGs.
Just get the system that appeals to what you like the most, and it's pretty hard for you to choose wrongly. Either system you get, you're going to probably be playing a lot of multiplatform games and both consoles have good exclusives. If you don't like the idea of paying for Xbox LIVE so much, go with the PS3 and its PSN. Just be aware that the PS3's online play isn't quite up to snuff yet, and the system itself is not as user-friendly as the 360. Also be aware with any multiplatform games you buy on the PS3 that the 360 will always be the leading SKU, so they'll tend to look and probably play slightly better on that platform (if you care about such things. I generally don't).