Against Manchester City, it'll be a very difficult game to predict because Manchester have won all their four league matches and are sitting at the top of the league table. West Ham would be playing at home which I think is an added advantage for the Hammers.
In terms of performance Westham are playing very well but on the other hand Manchester City are one of the predators again and that is not in doubt. They are one of the 3 most prolific clubs at the start of this season apart from Tottenham and Brighton if you look at the goal productivity they have on the other hand, they are a club with a strong defence because of their attacks that make opponents unable to do anything but defend.
West Ham's advantage is KDB who still cannot strengthen Manchester City because even though Manchester City's attack is dangerous but in the absence of KDB in this squad, it slightly dampens them to rampage in the match but this also does not mean they can win because I believe Manchester City can definitely win 3 points in this match.