What Is The Best Psp Video Game?

Just like on any gaming platform (or your pc for that matter), there is no such thing as 'The best video game'... How good a game is depends on what kind of games you like... If you like driving games, and I like platformers, we aren't going to agree on what is the best game. So the better question would be - What is the best (insert type of game here) game on the PSP?
Some of the best games on the PSP by ratings are: God of War: Chains of Olympus, Ratchet and Clank: Size Matters, Daxter, Grand Theft Auto: Liberty City Stories and Star Ocean: Second Evolution (among others)... But these kinds of ratings won't tell you if you will like the game, simply that they are considered among the best games of their type available on the PSP.

If you want reviews and ratings on PSP games, as well as games from other platforms, I'd recommend you start at GameSpot, and look around there for a while, you'll probably find something that interests you.

Good luck, and good hunting!