Nowadays, I believe that football has become a little more unpredictable than it used to be. I would say that it is at least more unpredictable than it was in the past. I have always considered Real Madrid to be one of the best teams in the Champions League. Manchester City is also showing good form. Due to the fact that Manchester City is the current defending Champions League title holder right now, it is safe to say that they are the best team.
Honestly, I don't think that PSG is even close to their level, as far as I'm concerned. And if we talk about Barcelona I have to say that the Barcelona we have right now is not on track to win the Champions League.
barcelona was eliminated from the UCL and UEL last season, it shows that their performance is not stable for international events
even though it already has a good squad, barcelona is still unable to keep up with the performance of man city, madrid and bayern in the champions league for now, at the next UCL event i'm not sure barcelona will have big changes, it seems that xavi hasn't been able to afford that
I agree that Barcelona performance has been very poor when it comes to European competition, but xavi would be having another to strengthen his club after seeing where all the faults is actually coming from so now should be best time to build that Barcelona squad once more but I doubt that Barcelona could ever reach up to their standard of old because at that time they were in possession of the world most creative players and I think a team of such standard would be the man city of today and it wouldn't be any surprise to me if they could actually secure the champions League again.