It is always difficult to determine who will win the Champions League title, especially when the season has not started. Manchester City certainly have a chance to repeat their success, but to defend the Champions League title then I think it is the most difficult challenge for any coach. Pep Guardiola is expected to keep his chances good, but all the teams that will be competing in the Champions League will also be pushing for the title.
Yep, Barcelona is the biggest contender in this league, Bayern Munich can be a strong contender as long as they can sign Harry Kane.
For Real Madrid, PSG, Inter, Milan, Arsenal etc, they're still in development phase to find their best eleven players.
Surely Manchester City is still look as the strongest club, but they're not yet in the same level like Real Madrid in 2015-2017 seasons where no one can compete against them.
Even here I partially agreed with you but still I have feeling most chances Manchester City is strongest but Bayern Munich after having completion of their transfer with Harry Kane going to be one of the toughest opponent for them because Barcelona is also under development with many other clubs which you already mention, and they can't give challenge to these two teams which are having good solid squads.
But, we have another factor if Real Madrid completed Mbappé deal then it's going to be another contender for the title even it's just personal view but still things can go in this way as well sadly few Italian sides are facing finances issues, but we can expect another good season from them like they have in last season but due to big gape of money things are clearly going for the English clubs to stay at the top.