PSG and City are fighting for the title very carefully, they really need it and in order to make all these spending count for something the league titles are not enough anymore, they need to win something in UCL to keep this up, otherwise it would not make any sense at all. I personally believe either City or PSG will win it and finally have the happy ending they wanted.
PSG and Manchester City have spent a lot of money building their squads just to win the Champions League title. But unfortunately despite having a strong squad, they are not performing well in the Champions League. But both PSG and Manchester City are very strong this season. My guess is that one of these two teams will be able to win this season's Champions League title.