I hear the Evo 4G can run PSX emulators well enough, so I'd highly suggest looking there. The PS1 in my opinion is the undisputed kind of RPGs (followed by the SNES). There are so many that I don't even know where to begin. If you're willing to invest a large amount of memory space towards games (multiple gb in some cases I believe), there are the multi-disc games like a lot of the Final Fantasy games. There's Chrono Cross, Legend of Dragoon, Final Fantasy Tactics, the Lunar games, Threads of Fate...
I could go on for days.
As for GBA, which is another great emulator to consider because it works so well on phone controls.. Golden Sun 1 is among the best of the best on it (GS2 doesn't work however =(..). Final Fantasy Tactics Advanced is a lot of fun too (it's completely different from FFT for PS1, it's not a port). I'd say FFTA is my favorite on GBA, but most seem to side with Golden Sun. And then of course there are the Pokemon games. They're a lot of fun on the phone man. No shame.