Either Kingdom Hearts as it was my first ever PS2 game, or Final Fantasy X, as it was my first Final Fantasy...
I'd say FF X, then KH, then FF X-2 then anything else by Square Enix
As it was my first game in the series FFX is tops, not because i think it is the best, but first = special. X-2 becuase it is the sequal.
I will always love the FF games but my lil bro got me hooked on the GTA game now. Its always nice to pretend that any ho on the street is ur co-worker or anyone that buggs and u can just smack them around lol