Only games from the main series are included in the poll.
Assassin's Creed has received a lot of flak over the past 3-4 years for many reasons, but perhaps most notably for "not innovating enough on the gameplay" and for "becoming a yearly release" (which wouldn't inherently be a bad thing but there seems to be some sort of stigma about it?).
But with that said, I've always loved the Assassin's Creed series for their historical settings if not for anything else, and I'll be the first in this thread to admit that I'm looking forward to exploring 19th century England in Syndicate. (I suppose I should also admit that I didn't play the previous two games in the series at all, but that was mostly because of the pricing).
With these games, I've always felt myself completely immersed in both the era and location the games have offered, and there's just something magical about that. The combat might be a bit monotonous and the story unreasonably complex and confusing at times, but eh, I like 'em nonetheless.
I included the text above for no other reason except to hopefully prevent any flame wars from happening, though I should hope that the games haven't become quite that hated. In fact, I might be misreading a bit into just how much (or little) hate there actually is. Negativity tends to stick out more than the good stuff.
But, onto the actual question! Which Assassin's Creed is your favorite?