The French winger was wanted by both Manchester clubs but joined City in a £24m deal from Arsenal.
Now, after winning the Premier League with the Blues, he said: "When I was considering both clubs, City's football development chief Patrick Vieira's argument was that Manchester United are used to winning everything.
"If I had signed for them and played less well, it would not have been a success for me.
"Whereas City are building for the future, recruiting the likes of Sergio Aguero, and if I won the title with them, I'd be part of history - so I came to City to help the team become champions.
''I have achieved that and now we want to win the title again and go further in the Champions League.''