City defeated Swans at the Liberty on Saturday.
Britton, 34, said: “In terms of passing, I've been playing in the Prem for five or six seasons and I don't think I've played against a team that treats the ball as well as they do with their movement."
It is not City's awesome firepower that gives them the title edge, it is new all-singing, all-dancing Chilean sweeper-keeper Claudio Bravo.
Britton said: “The keeper is like an extra player. You think you've got them, you press them right up the pitch and then he comes to the edge of the box, drops a shoulder and beats a player in his area.
“There was one incident in the first half where we chased him down and he clipped the ball over all of us to Kevin De Bruyne, who was the free man on halfway. And suddenly we were one against three.
“Something like that makes them very hard to play against. They are definitely one of the best sides I have faced in the Premier League."