Have both PSP and NDSL, and NDSL is without a doubt better.

I think it's because it's more interactive, and IMO, I think that the multiplayer games on NDSL are much more fun compared to PSP

My BF also used to say PSP was better than NDSL until I got on the other day, after one week he couldn't resist and went out to buy another NDSL too. Now our PSPs are just sitting in a corner, collecting dust