Wizards/Piscodemons and all variants. I hate them all.

Alas, in all my FF1 playing, I have never, ever met Warmech. How's that for misfortune?

and I always have 3 mages. Whitemage, Blackmage, and Redmage
For supreme happiness in the pants, try three Red Mages. Slight limitation on spells, but so intensely easy to level up.

If you like to power play once in a while.