Most Interesting / Strongest Final Fantasy main antagonist?

I chose ExDeath because he was by far the strongest of all bosses.Plus FFV was the first Final Fantasy i played.Sephiroth was not that hard and so was Kefka and Zeromus as well as the Dark Cloud and all the others.And this is my 2nd favorite battle theme,the first being clash on the big bridge.

It kinda just goes to show that Square-Enix/soft doesn't really make hard bosses. >_<;