The 4 Elements in FF1/FF4 were EPIC imo.

This battle was a really wicked battle though for Edge, and the fact that Edge had to avenged his parents makes it even sicker. They're transformed into monsters by Rubicante (and controlled by him or Zeromous). All your party is left to one road that leads to destroy them in their newly twisted form. Edge's King and Queen parents made Rubicant seem like a very sick evil tormentor of hell, and his fire spells give off the impression that he is truly the devil of all devils.

The whole story in FF4 is amazing for a video game of this time period. It towers over ALL FF in existence imho. Based on game battle system strategy, art mythology, storyline, characters, boss fights for sure. This games soundtrack has influenced every RPG in existence imho also. Themes of Darkness to Light, Murder/Genocide, and mind control were all done to perfection in FF4. No game can touch this one, they can only be inspired by it imho.

"...And"

Everything about this fight just worked for me on such an amazing level.

Aesthetics; mechanics; soundtrack... it was all just perfect.

Doom Wall from Final Fantasy 4

Sand Crawler from Final Fantasy 5

Gil Turtle from Final Fantasy 5

Shiryuu from Final Fantasy 5 (harder than last boss)

Beta from Final Fantasy 5 (harder than last boss)

When a mighty and powerful Moogle guiding you takes the long way around the desert, instead of that shortcut a few steps through the middle, you should too! Hmm, perhaps it's time to go back and play FF5 again...  I could really use a modern remake of that game!

The first phase against Ultimecia's regular form is nothing special, imo. When she summons Griever and Maybe I'm a Lion starts playing though... holy shit. And then comes her final form with The Extreme and it's just... wow. Granted, FFVIII is near the bottom of my list (though I kinda like it) and the battle is pretty easy (mostly because of how broken the game mechanics are =P), but it's easily one of the best final bosses on the whole series.

Shiryuu is bullshit. Who the fuck puts a superboss inside a regular chest with no warning?

I couldn't have said this any better :)

Fighting Betrix at the end of disc one