Forgive me, but if it were a fact that Final Fantasy Seven is generally better than The Legend of Zelda: Ocarina of Time, then there would be very few arguments about it.
Unfortunately, we live in a world where more opinions exist than facts. You cannot argue that FF7 is a longer game than Ocarina, or at least, not in terms of play time, because someone on his first play through both games may have finished FF7 with less time on the clock than Ocarina (and it was probably the owl's fault

).
You can't argue that FF7 has more enjoyable sidequests. I actually had no fun at all going to the Gold Saucer and playing games and breeding chocobos and stuff. And training for Emerald and Ruby Weapon... that got pretty boring after a while. Granted, it doesn't involve as much frustration as striking every cubic meter of Hyrule Field with the Megaton Hammer to find that last Gold Skulltula, but there were some sidequests in The Legend of Zelda that would have provided much better entertainment for some people.
I actually thought that Ocarina's graphics were superior to the original Final Fantasy VII's... As for music, I much prefered FF7's style, though I found it inferior to Ocarina's musical quality. It sounded less digital.
Storyline is a very difficult thing to argue. Especially for me, being someone who cares more about the characters. I could go into Ocarina's advantages over FF7 with characters, but Ganondorf makes that hard for me... especially when he is up against Sephiroth. But let's face it. The storylines of the two games have nearly nothing in common, so people are bound to develop likings to one over the other, and not everyone will prefer FF7.
As for gameplay, FF7 is turn-based. You need more strategy than skill. Zelda is exactly the opposite. Again, this causes opinions to differ greatly, depending on one's tastes.
Sorry to ramble on. Just stating (through that biased-towards-FF7 speech of mine) that everything you could possibly argue for one game over the other will be completely opinionated. And I suppose you could say that that, in itself, is an opinion.
But for many reasons I have not stated in this post, I must say that FF7 dwarfs Ocarina of Time any day of the week. Of course, that's just my opinion (don't these opinions just drive you crazy?

).