This trio is strong on paper. Yes, let's say if you take Neymar from the time when he tried, the young Messi + Mbappe with a stable psyche, when he was not yet mired in money and jealousy, then it would be very cool. But in the existing reality, Neymar is good, but not as when he was considered the future undisputed top 1, Messi is old, and Mbappe is unstable due to many reasons. I don't like both of these clubs, but City >> PSG without a doubt.
If Paris Saint Germain have Messi, Neymar and Mbappe, then Manchester City have Haaland Erling who has played incredible this season. But there is something interesting in my opinion, they play as a team so I will make Haaland the main favourite. I'm not trying to compare, but now I see it that way, of course by seeing how they work together as a team, not individually.
Haaland is a good striker (maybe even become a great one) but in my opinion KDB is more important for City. Any top striker can be in Haaland's place - Mbappe, Lewandowski, etc. and show similar performance, but this will be a consequence of City's team play. There is nothing like that in PSG - they are still a team of stars from the farm league, there are no prerequisites for them to be consistently successful in the Champions League.