It has to be Jon Snow. it has to be.
He gets cut down at the end of Dance, but I don't think he stays dead. I strongly suspect Mel resurrects him with the Red Kiss next book (thanks madkasel). then he will fulfill her prophecy form Clash: AA will be reborn amid salt and smoke under the bloody star to wake the dragon from stone.
Jon's wounds are smoking in the cold - Bowen Marsh is weeping and teh giant is swining the dead knight overhead - his sigil being a star. i can't figure out the dragon bit yet - but I think Jon doesn't stay dead and I think he's AA.
Dany has a really strong case too - and she fulfills the bit about waking dargons - but where's the salt? and is the coemt running when she goes into the Pyre?
Davos - risen from salt and smoke under the star on the Blackwater - but he is even farther from any dragons. Plus - he didn't really die.
We all know its not Stannis - I really think its Jon Snow. I really do.