Hot Pursuit. Not a fan of sim either and IMO HP is the best car racing game this gen. 2+ years after it's release and I still play that game to death. I've come across players who bought Most Wanted and came back to HP because the online is more fun. While certain online modes don't get a lot of players, the Hot Pursuit mode gets regular traffic. I can regularly get into a full lobby.
My only complaint about the game was I wish Criterion had release new tracks/locations for online races.