I usually replay any game I own a lot. Ones with lots of story to absorb get played in obscene amount. The MGS games, Final Fantasy VII-X and I'm already on XII's second run (yeah I've played the old ones only once, I must be ebil), Chrono Trigger, Chrono Cross (didn't like it as much but I did enjoy it), Xenosaga, Kingdom Hearts I and II, that sort of thing.

Tales games with GRADE get my vote for best replayability,especially Tales of Symphonia and Tales of the Abyss . Their GRADE shops hold a lot of replay potential, and you even have to play a few times to work up the GRADE to buy everything you want. Then you can put it on a harder difficultly and gogo.