HP Plus and MP Plus negates natural HP and MP limits, so that's never a concern for me.

My single favorite limit break is Great Gospel, but it's defensive rather than offensive. I actually dislike Vincent's limits since he's uncontrollable, so I prefer using him in random battles instead of boss fights. Yuffie falls in between for me, neither the best nor the worst.

But Cait Sith still bottoms out my list.