Altair and Desmond were 6'0 (183cm) and Ezio was around 5'10.
The developers did say in the Inside AC3 videos he was heavier and bulkier than previous protagonists who they described as 'small guys in lots of armor'.
From playing the game my guess would be around 6'2. He doesn't look like someone who is shorter than or 6'0. Also the natives who lived around New York/Canada were described as very tall people.
Conor Kenway, the protagonist of "Assassin's Creed III," is depicted as being approximately 6 feet tall (183 cm). His height, along with his athletic build, complements his skills as an assassin in the game's historical setting during the American Revolutionary War.
Connor Franta is 5'9".
Connor Tkachuk is 6'.
Connor Fabiano is 6'.
Amber Connor is 5' 2".
Elizabeth Connor is 5' 4".
Janelle Connor is 5' 9".
Kristofer Connor is 6' 1".
Nathan Connor is 6' 6".
Sarah Connor is 178 cm.
Shane Connor is 5' 11".
Steven Connor is 6' 2".