FFVIII, because it has a similar taste to FFVII.
BUT, if you want to feel like how were the first, and more classic Final Fantasies, you should play IX. It's like a love letter to older fans (like me) and as a game, it's just masterful.
Go for FFVIII and then for FFIX, because if you play IX first you'll feel FFVIII like a lesser game, which it isn't IMO.