I would wait for a Wii... If they're all sold out, it means that everyone wants it... because Wii rocks
I've had more fun with SMG, Zelda and other on Wii, than most of other games, lately.
Otherwise... all for 360. PSP just hasn't any good game on it. But it really rocks for homebrew and emulators
The last game I played on it was Silent Hill Origins... not a bad game, but it really doesn't hook you up.
The only games I've really played on my PSP?
Monster Hunter Freedom 1&2, Guilty Gear Judgment (the JAP one... because it has GGXX: Slash), Evangelion Tsukareshi Sekai, LocoRoco, Megaman Maverick Hunter X, Me & My Katamari and Taiko no Tatsujin Portable