for my 2 cents....I've never owned the GamePark but, I do have a 1.5 PSP with EMUs, games and movies.
The ability to play ISO's, movies, TV shows, photos etc etc really easily on the PSP wins my vote.
So far the on only EMU that I'm really impressed with on the PSP is the Neo Geo CD. It plays about 19 games flawlessly (no music though) and they are of course mostly "marquee games" (ex. Metal Slug, Fighters History etc).
The SNES and Genesis emus are interesting but don't work very well.
The Visual Boy advance for now is more concept than actually working....and so far that's about a far as I've personally dived into the EMUs.
I have a feeling though based on the user installed base for the PSP, you're going to see the most advancements on that machine over the GP32. I'm sure most of these EMUs will only get better on the PSP over time.
