I liked Final Fantasy X too.
Ronin, there's a Street Fighter Anthology for PS2 that has SF2 and SF3.
If you like adventure games, Tomb Raider Legends is good. I think all of the PS2 Tomb Raider games are supposed to be good.
You should definitely try Katamari Damacy! Also, definitely ICO and Shadow of the Colossus!
I have no idea what FPS are good for PS2, don't own any. I'm sure there must be plenty, though.