10 Blizzaga, 10 Thundaga, 10 Firaga, and 5 Cura is more than enough for any mission in the game. (I replace Thundaga with Aeroga for the six giant heartless mission) >_>; That was my set up of spells from a bit before day 250 until the end. Looking back, I rarely used Firaga and should have replaced it with either extra Curas or a stock of Cure, but it all worked out well. I always had a nice stock of magic to back me up through the game, and it made many of the more ridiculous missions that much easier for it. Always having those pocket Thunders to finish off a particularly nasty enemy is very very helpful.
So I swallowed my pride and played with the Zero Gear. .-. I have to say it was pretty nice, though its air combo isn't much better than the Omega+ combo. Omega+'s second hit has a massive chase effect built in, making it pretty sweet. Its finisher is just about as powerful as the Zero Gear's, albeit weaker due to lower Strength. (I put 4 Power Units into the Zero Gear, since its abilities are next-to-useless for post-game). Having over 200 strength is nice and all, but I feel critical hits are vastly more valuable than massive strength. (This furthers the Zero Gear's superiority, so shhh). Critical Sun +4 Sight Units = 46% Crit and 79 Crit Bonus for my level 71 Roxas. That's ~10% higher than my Omega+ got and about 20 or so Bonus points higher. >_>; 186 Strength is about the same as when I had my Omega Gear+, so yeah... I'm finding it difficult to argue that the Omega+ is superior in any way aside from ground combo, but... even then, the Zero Gear has the Y ability in there after you pop them up to cut them back down, so I dunno. Omega+ has more fun against the Orcus. :< It can chase him around with its aerial combo, hitting with the finisher with much more frequency than the Zero Gear.
I'd still use the Omega+, though, if only for Brick Wall and Magic Bracer. Those two abilities are really nice, especially when fighting weaker enemies like Gigas Shadows who barely injure you but knock you out of the combo all the same.