I think you're honestly wrong, in my opinion Real Madrid gives more importance to the Champions League, in fact the season in which Barcelona won (two years ago) they actually abandoned La Liga to focus on the Champions League. I don't know about Manchester City, but for Real Madrid the priority is the Champions League.
Champions league have been the most loved league by all team and any team that gets to participate in them will strive ti make it far because of the plenty benefits that comes with playing them and bonuses from one stage to another in the competition. A lot of teams will prioritize the champions league ahead of all other competitions they’ll be playing in but that is not the case for some teams that knows they can’t go far even if they try. It’s a choice and every team differs on how they see it, as for Real Madrid, I think they value the champions league more that the La Liga.
PSG cannot be underestimated even though Mbappe is no longer playing there because PSG's game next season will be much more solid because they don't have to think about one person. Luis Enrique is one of the coaches who has the ability to bring PSG to play better and I'm sure they will be much better than last season.
So PSG have always been depending on Mbappe all this years? Now that he has left they’ll have to ride on their own and I don’t think they’ll have a hard time to get on themselves and let it go. PSG is not a weak team and with the quality of players they have now, they can as well be champions and go far in the competition. Luis Enrique is a trusted coach and I’m sure he won’t fail the team this season again.