I've only seen Omnislash, so that's what I would've voted for. Haven't seen Lionheart yet, but I have that weapon! I just have to get Squall to perform it...
Ah, I'll try, but he always manages to kill monsters with just Renzokuken. Then Rough Divide, or Fated Circle pops up after that, but I'll get it one of these days.
Its probably a bit unfair but I put Blitz ace and attack reels in there lol. Just because they are awesome limit breaks which can compare to those previous 2.