it depends on what game is out n hot at the time...right now, it's psp coz i play Crisis Core, last time, it was NDS due to Apollo Justice...and the cycle goes on.

So if u wanna choose, choose what games are u going to play...then it'll be easy.

btw, I bought NDS first coz of phoenix Wright and no great games was out for the psp at that time. Most that's out that time are ps2 ports. Now...there are lots.

If u want something easy to carry around n longer battery life...go for NDS. If u want crisp graphics and out of the box media player (NDS hv media capability too but have to buy R4 or the likes), choose PSP.