I never did finish FFVI but I got the vague feeling these two are pretty similar. Kinda the same role as the Noble Demon who works for the Evil Empire but isn't a bad person themselves.

Thinking like that, I guess Cecil also fits...but he literally leaves the evil empire five minutes into the game and he's the main character, not an antagonist.

Still, who do you like more and why? A lot of people liked Leo, I've gathered.