Anyone that said FF7 is wrong. Not only is it not even REMOTELY the best final fantasy game(6 is, even though I prefer 4,) it has not aged well, at, all. Everything up to and including 6 aged very well, they are what they are, but 7's polygon thing? Yeah, didn't age well. 8+ aged reasonably well.
Now that that is out of the way, The best game ever, hands down, has to be Chrono Trigger. Music, atmosphere, a time traveling game that doesn't suck, old school JRPG style combat, brilliant characters, Dinosaurs, robots. It just did everything right for a JRPG.
These things are my opinion, and I will probably stick with them. I don't hate 7, but to call it the best game ever just doesn't make any sense to me.