Alright... I'm a little confused about this thread...

Is this hate as in "damn they were just a terribly lame villain" or is it "damn that person pisses me off, they are written so well cause they proceed to invoke such powerful emotions from me."?

I'll do both.

Seymour is the lamest villain in the series by far cause he is irrelevant to the plot of the game he's featured in. I believe he only exists cause the creators felt the player needed an antagonist they could talk to.

His crimes are weak compared to what every previous villain and even compared to what Yu-Yevon/Sin was doing in his own game. His motive was lame and I am sick and tired of these childhood crybaby stories. If you mentally remove him from the game you quickly realize that it hardly alters the plot in any significant way. He was practically the game's "flunky" villain, every time he shows up it's like...

Seymour: I'm here to smite these cause I'm crazy in the membrane!
Party: You again? (party bitch slaps him out of the way and proceeds to continue the plot)
Seymour: I'm here again to smite thee!
Party: WTF!? Didn't we kick you ass already?
Seymour: I'm different now! I'm ZOMBIE SEYMOUR!!!
(Party proceeds to bitch slap him out of the way and continue the plot... rinse, repeat, ad naseum...:rolleyes2 )

For villains that drove me to hate them cause they were done pretty well... I'm going to say Golbez, even if he wasn't the game's main villian he was still a man that drove me mad. Every time you meet him he finds new and more amusing ways to screw your party over. Whether he's brainwashing your friends, stealing crystals or just messing up the place he always seemed to be in control.

You literally spend most of FFIV just trying to catch up to him but he always finds a way to stay one step ahead of you. But you had to respect and admire him. He dressed snazzy, he was more powerful than you, and far more intelligent.