As for handhelds, the DS imho is the best choice for Nintendo style games, with the best controls. The touch screen really adds depth in some games, control wise, and also provides great stats! (mainly live maps that show objects as you get closer or as they get closer to you)
I also own a psp, and have to say, the game play on those is far too technical, and the screen offers very little enjoyment, it's a beautiful machine, but just lost all functionality when the glare and brightness don't do much help. The current ds i've got, on the other hand, has the older style non adjustable brightness, and it's sufficient in most cases, unlike the psp... which you would think is far more superior to the ds.
But... if consoles are more your thing, check out the latest systems and see what games appeal to you to better make that decision.