Manchester City is strong but I think you are not giving Chelsea enough credit. Manchester City has good team but they have some weaknesses in defense and midfield that Chelsea could take advantage from. Chelsea has been playing well recently and they will probably give Manchester City hard time. I agree that both teams will score goals but it is hard to say who will win. Chelsea might be able to use Manchester City weaknesses to get tie or even win game. Match is going to be exciting and very competitive.
Manchester City are in a slump, they are weakening after finishing last season well but this season they are really under heavy pressure, especially after the defeat in Paris I think it will be difficult for Pep's team to recover quickly, many factors have caused Man City to slump even more, especially the performance of the players on the field has started to decline and the mentality has faded a little and I think Man City will need time to recover, Chelsea who are currently arguably quite good in terms of player performance are more impressive than Man City and I think Chelsea have a higher percentage than Man City in the EPL match.
Playing at Man City's home is not easy for Chelsea from the last 5 matches at Man City's home Chelsea have never won, but I see the performance this season or currently Chelsea is superior and their away games in the EPL this season are quite good and I think Chelsea will come out as winners.
Chelsea playing at Manchester City home will be a difficult match to predict seriously because currently Chelsea are in better form, meanwhile Manchester City are not that too bad to be underrated against Chelsea, even though Manchester City are not in their best form this season.
We should remember that they will be playing at home, so I think home advantage will be there, and since Manchester City is not a very weak team to think they won't win, I don’t think it will be possible to say Chelsea will be the winner; rather, let's see what will happen then.