In rough order:
Ico/Shadow of the Colossus
Uncharted
Jak & Daxter
God of War
Dark Cloud
Of course, Uncharted isn't really a franchise yet. Man, I can't wait for Uncharted 2 at the end of next year.
And I'm sure LittleBigPlanet and Killzone will be making this list upon release. ^_^
I would include Ratchet & Clank and Sly Cooper, but I don't actually own games in either franchise. :(