Definitely CT

FF6 has a better overall narrative and characters, but the game is a pain in some spots to play what with the high random encounter rate and forced party split ups and in which you'll need to grind all the characters as they don't level up with you.

CT like FF6 has a great soundtrack, kind of a lackluster story in comparison but the game design is bar none above FF6s. As is the gameplay in many respects.

Lube Me Up