Definetely the PSP, you can do a lot of stuff with it and it has more graphical power than the PS2. It has not been selling as as the DS because the DS is targeted to a younger audience, but Sony is starting to get some pretty good games for their handheld and also with the "new" Slimm version coming, the fate of the PSP will probably be changed.
This user is completely without Sig... Sigless. Not at all Siggy wit' it. This is an ex-Sig.