I'm typically a Nintendo fan and Sony hater but I recently decided I should have both handhelds. So I have a few questions naturely. I know all platforms fairly well but am wondering.

What is the best FPS hands down on the PSP?

What is the best RPG hands down on the PSP?

What is the best platformer hands down?

The best Real Time Strategy?

I think you get the picture what are the best of the best the PSP has to offer that I'm missing out on with my DS? 

RPG: Crisis Core, Jeanna D'arc, and Lions War.

Rpg: Crisis Core for now , but Kh BBS will take that from it.
FPS: Um I don't think there are many fps but socom is a good strategy tps.
Platformer : Loco Roco

Fps: Syphon filter series (the first and third part can be downloaded from PSN for a few bucks and look awesome on such a small screen) Medal of honor heroes, socom.

RPG: Crisis core!!!!!

Platformer: Patapon, Ecochrome.

Also worth checking out: God of war, daxter, metal gear solid portable ops, GTA games, Sega genesis collection (lots of fun) and most of these games can be found for bargain prices.

Edit: Sid meyers pirates is the best rts from what I have heard.