Hmm. Warlords have the tools to win now, but most people probably aren't sure how to use them yet in an innovative fashion. Therefore anyone who is good with warlord and can come up with an innovative and effective warlord strategy would have the advantage of surprise. All this is the same for the Malakai priest but to a lesser extent I think.
How much I expect each Mage to win the tournament (out of 100%, divided between all 14 mages, not taking individual competitive players' Mage preferences into account):
1. Bloodwave Warlord 20%
2. Malakai Priest 15%
3. Anvil Throne Warlord 15%
4. Priestess 20%
5. Something else 30%
Of course, now that I've said this people will be more on the lookout for innovative Warlord strategies.