I think you didn't do your research very well,if not you would have know that Tottenham Hotspur are also unbeaten this season also, for me this season will be very tough for everyone, I agree here that Manchester city are the favourite to lift the trophy but am not disputing the fact that other teams are up for it too, one thing is certain this season is not going to be a two horse race between Liverpool and Manchester city, this season will be tough and team like Chelsea, Tottenham Hotspur can come up as dark horse and win it.
You are right this season is surely going to be amazing even many teams are declined in quality but still good competition specially after we have good results from Manchester United which is going to be more entertaining Manchester City is surely at the top of the game but right now Tottenham Hotspur, Arsenal, Liverpool and Chelsea which are struggling can do impressive run and tough challenge for title race in coming weeks.
Few teams having not good start of this season but as time will run and their players will settle here we will have good change in league table with good teams are surely going to be on their right spots which they deserve with current situation we can't say anything about title race because until winter nothing is clear, and many changes can happen.