i agrea the vilan does play a large part in how wellt he story develops if you have a poor villan then there doesnt seem much point in tackling him but im glad to say all the ff's ve played have decent villans including 6.
Kefka is one of those annoying guys you just wanna kill or something so it makes him a god villan imo.
Saying that i didnt really like Seifer villan wise he had all the aspects like he strides through the game with some cocksure atitude but i just didnt like him.
Anyway you will enjoy ff6 thoroughly recomended.