Personally, I find a lot of Aerith's redundant or just plain useless but at least they tend to suit her skill set and stats.
I rarely use Vincent's limits since you can't control them and frankly they're a pain in the ass, especially with a lot of the bosses requiring more complex strategies.
Tifa's are of limited usefulness against many monsters and Cait Sith's can be a risk that aren't worth it with the exception of higher-leveled Dice.
However, Barret wins(?) on Mindblow alone.
Which character has the worst Limits?