Wow, tough call. I think I'm going with Hitman since I believe it will snag the most GOTY awards this year and I honestly believe that it is the better of those games.
Assassin's Creed III looks good but also appears to be 50% QTE's, Dishonored is way too short and the levels are a tad boring in design and variation as are the enemies and the story is unoriginal at best.

I'm going for Hitman on this one!

halo 4 as the best assassin game, it always finds a way to sneak into every category

Dishonored easily. Will get the highest Metacritic, is a new IP and is much more sophisticated and original than the competition.

Hitman, no contest. Dishonored is awesome but still very rough in certain areas. Hitman looks really well put together so far.

AC3 easily

In the last hour I've discovered just how underrated Assassins Creed is.

How come? Based on the disappointing reviews or negative comments here on VGC?

Halo 4 has assassinations so the answer is Halo 4. Of the three you listed in your poll only Dishonored interests me.

You should never hit a woman unless she is going to jail, now.

Mix of both plus comments. The reviews especially in relation to those of the previous games, which are out-of-sync of my own perceptions of those games, and the comments which so far seem to be overreactions. Getting the game at midnight so hoping I don't find them to be right (really hoping the Mass Effect 3 ending is the only one where I find out the reactions were justified).