This is such a difficult question, I love all of the new jobs more than I thought I would.
I personally feel that COR will not be pure support, and will have potent damaging attacks and spells along with their support abilities. What makes COR so great to me personally is that it's going to take a real master of the game to wield it effectively in all situations, since things can go sour so easily using nothing but luck and chance (although luck enhancing gear will undoubtedly be present, and be extremely coveted by COR enthusiasts. Expect anyone who isn't a COR to go "who the hell would trade 3 mil for 5% more luck?") and thus someone with a quick mind and knowledge of how the game works will be needed to turn things around. Hopefully, only smart people in general will be interested in COR and it won't have a bunch of people playing it just because they want to be pirates, because that would mean no one would ever invite a COR due to the undeserving reputation they get...kind of like what happened to Dragoon, or Dark Knight.
Puppetmaster is...amazing. It's taking the effective power of hand-to-hand and gives you a pet capable of being customized to suit any type of situation. People also will like a PUP in the party in general, the puppet will probably have a certain amount of charm to it. For all accounts and purposes, its a job you create from the ground up, with a lot of promise. My one problem with it is that it was originally supposed to be NEC, but SE had some excuse that they didn't want "undead going around in the daytime" which is stupid. But I appreciate them being different about it.
The ultimate job is Blue Mage, though. The totally new and unique system of how BLU selects its spells for usage will, much like PUP, make it an open-ended job. BLU can make themselves a damager, nuker, support, or healer with the system that's been set up, and BLU itself will acquire VERY powerful techniques in each of those areas of the game.
The ability to possibly become "undead" at endgame, or in general, I feel will also be interesting. But, what would the penalty be for overusing your magic and possibly the undead ability? The way the BLU description goes, a BLU has to refrain from succumbing to a more base level of instinct, and also has to be "willing to sacrifice a future for their duty" which leads me to believe a BLU will get EXP penalties for overusing their magic. Something a little more advanced would be the undead mode taking away exp in proportion to the HP they lose after hitting the 0, with a certain limit of course. A common thing endgame BLU would do in HNM situations is level up their buffer as high as they could, and combine different spells like a suicidal self-destruct with the zombie status to sacrifice entire levels they've accumulated to do good damage to a mob before the effect wears off. I can think of no other ultimate sacrifice, and I'm confident SE is putting a lot of hints into how the jobs work in those descriptions they put up.
I personally like BLU, because of the amazing power it holds, and that in the event I'm correct about something like that, the penalty wouldn't mean much to me, a person who's very used to throwing their life away for everyone else. I could do without the rather absurd looking AF hat, but I like the rest. I like COR and PUP as well, but I like and appreciate every job in the game, because SE has a very sound and effective way of creating things.