I think thief, ninja and samurai were the most popular ones being asked for. Theres a huge pool of classes to pull from within the Final Fantasy world, no doubt we'll see some classes return from FFXI in a new flavor and some we havent seen in an mmo setting before.

I personally would love to see samurai, machinist and gunner make appearances and there is stuff in game already supporting other classes such as puppet master.

I look forward to see how they interpret them into FFXIV or even come up with something completely new.