I hate when you say things like this!
Zodiac isn't that great anyway. I only got it for bragging rights. You could just as easily use Cyclops or Bahamut.
How do you get more than one person to get Zodiac? When I get in there against Elibdis and his buddies, I have one summoner with that Support ability that makes you take damage to your MP first, so my Summoner can actually survive it. I have my other four guys killing Apandas and ugly old guys. Perhaps if I came in at a ridiculously high level, I might be able to bring in 5 Summoners... But the prospect of no physical attack power is scary.
It would be nice if you could cast summons on your own party, just for the sake of teaching Zodiac to others.
But, on topic, I like the Monk best. They can hit hard, and have a very diverse skillset, from devasting moves like Earth Slash, to happy fun moves like Chakra. Honestly, their pure attack is more powerful than Earth Slash, Repeating Fist or any other. Earth Slash is just nice because it can hit more than one guy, and when you hit 4 or 5 guys with it, well, it looks awesome.
As far as non-generic, I like Astro-guy. I can't remember if it's Astronomer or Astrologer, so I'm going with Astro-guy Olan Durai. I mean, Galaxy Stop. Seriously. When I first saw, I was begging God or Saint Ajora or whoever to have this guy join my team permanantly.