PSP will emulate arcades, SNES, Genesis, Amiga, 3DO, NeoGeo, PSX (!), N64, DC, XBox, PCs, Apples, GP32, GBA, DS, my granny, but above all it will emulate PSP perfectly! So PSP is the real winner!
Please don't say things like "the winner is this one", "the winner is that one"... I think there are no winners in the homebrew scene. There will be more powerful handhelds in the future, but the old systems will always exist (I hope my SMCs will have a long life...): i.e. have you heard about "Grand Theftendo"? A crazy (but amazing) guy is making an appearantly wonderful GTA episode for the NES, and the NES is... how many years old is it?