FF1 (nes): Opening scene.
Also, the first time I met Garland a second time and he turned into Chaos. It was astounding.

FF2: Guy can talk to animals! Yes!

FFIV: When it was remade by Necronopticus.

FFV: Faris Nekkid!

FFVI: Resurrection of General Leo.
Also, (SPOILER) when I discovered the Quick/Gem Box tactic (all by myself) that allows a character to make an infinite amount of moves in a single turn! Or, in that case when I tried it, the only time I did it, the most important time to do it, when Terra took every single hit point from the final boss, heavenly Kefka or whatever, before he attacked my party once!
BWAHAHAHA!