PSG and Barcelona in my opinion will be the favorites next season ahead of Real Madrid, Manchester City and Bayern. I don't anticipate them to be any weaker for a good reason. Both of them are not losing a lot of players due to transfers as far as I know as of now and both teams have the majority of players being at the perfect age and all of them are humble and willing to improve.
Next season UEFA will be a different kinda ball game for the team you mentioned, fighting for the UEFA trophy. I don't think PSG and Barcelona will be more favored in lifting the Champions League trophy next season, as other teams are making new signings to their team, to boost their formation.
PSG and Barcelona had the best season last season, next season we don't know if it will be the same treble and double trophy will be won by them next season. Last season, Manchester City and Real Madrid won no trophies; who could have thought of such? Next season, such a surprise could happen to PSG or Barcelona to win a single trophy, and it may not be the Champions League