well, the average gamer doesn't play every game for thier console. So no matter which one is bought, the person will have fun playing no matter what because there is a large share of good games for each console.
Which brings it back up to being an rpg or fps fan
If you look at the release dates for both consoles, they both have a great game line-up (i suggest you do this to know what games u would want to play). Just because a system isn't selling well, doesn't mean it has crappy games. There is more to it in selling a console in just having good games. Look at nintendo GC, it has a very large share of good games. Many people don't even know about some of them because they just brush em off because they are not from a well know developer. Also, most of the rpg's on the systems aren't even brought to the US/EU because the fan base isn't as high (just go to an import site and look for yourself).
But i have to agree that ps2 has much more games.