FFVII. Both are fantastic, had huge impacts at the time and I've replayed them both plenty of times. They are both within my top 20 games of all time. I've heard a lot of arguments that they didn't age well, but I don't agree. I think they play as well today as they did when they released.
Ocarina of Time is my second favourite Zelda game, FFVII is my second favourite Final Fantasy game. I give it to FFVII, because I slightly prefer the story, music, characters, world and materia system over Zelda.