It'll probably be Gronk, but I voted for Hernandez anyway. I felt like towards the end of the year and playoffs, teams would put five guys on Gronk in the redzone if necessary (although they still couldn't stop him.) Hernandez seems to be getting better, and I think he will be just a hair behind Gronk for offensive production next year (not blocking, just receiving.)
I also think Hernandez benefits most from the addition of Lloyd and Gaffney. It's amazing the amount of yards after catch and breakaways he had last year with a pretty short field, as there was no deep threat bring the safeties back. I think in a shotgun spread offense, say Welker, Gaffney, Lloyd, Gronk, and Hernandez, AH becomes the most dangerous weapon. He can just do too many things.