I'm kinda torn, though i love my PSP1000 i have been spending a lot of time on my DSL lately (blames Castlevania: Dawn of Sorrow). But i would say the PSP is still my favorite portable console if only for the awesomeness of DJ Max Portable (any iteration).
PSP 1000 for me, okay they're not selling it anymore but I can probably find one second handed. Otherwise I really wouldn't know. I'd probably invest in a good phone instead so that I can watch my movies on that. DS is nice, perhaps I'd enjoy it even more than my PSP if my GF would have one as well.