I really do believe this is the Final Fantasy with the best written antagonists
Depending who you liked the most, but personally Emet Selch. I was watching a video by Stout Helm concerning him, and definitely agree this is Square Enix's best made antagonist so far.
Heck HW's antagonist or antagonists is almost kind of equal to it in my opinion.
Now I guess it is fair to say that this is a more modern FF game compared to the classics, and if were remade today things would be quite different (a more fleshed out Ultimecia would be interesting). It would be like comparing apples to oranges maybe?
Gets me excited what FF XVI is going to be like.