Pretty sure the poll isn't working properly. I just voted in it and it said '0Votes'
I was expecting 2 to be the winner here as it is for most people, but I get why you chose Brotherhood, it's the best balance of all the aspects of the series. Different aspects may be better in different games, combat better in a couple of them, storytelling better in others etc, but it's the one that has them all with good quality and no real drawbacks.
For me personally, with the combat being the most important factor, I actually put Brotherhood as my favourite as I felt it had the best combat, it had everything I loved about it in AC1 but also forced you to think about your opponent and adjust your approach accordingly. I also felt that the characters were better realised in Brotherhood.
“It's a movie. If you are going to believe and be affected by an action film, you shouldn't go to see Pocahontas because you are going to think you are a Disney princess” Chloe Grace Moretz, what a legend.