I have played all the console titles of AC, and tbh this is how my list would go
1.) Assassin's Creed IV: Black Flag
2.) Assassin's Creed II: Brotherhood
3.) Assassin's Creed III
4.) Assassin's Creed II
5.) Assassin's Creed II: Revelation's
6.) Assassin's Creed
The reason I placed Black Flag in the top position was because I absolutely loved the game, and the idea of it. Also the main character Edward Kenway, unlike the other 3 (Conner, Ezio, and Altiar). He wasn't raised to be an Assassin nor a Templar, he didn't give a damn about either faction until late into his game, ran down a fully trained Assassin on foot. He was in my opinion the Best at what he did U_U, but dies in an un-favorable fashion lol.