PSG have no claim to being the best team in Europe. If anything they were fortunate to even play you because Napoli were the better side in both games in the group stage, and they got outplayed completely by Liverpool at Anfield. Their saving grace was that they didn't slip up in either of the games against Red Star. You're entitled to your opinion but I do feel you're overrating them somewhat because they outplayed you, when really if you look at their performances in Europe as a whole, they aren't the best side.
Tuchel won the tactical battle, that's what I'm saying, hence why they found it so easy to nullify you. I don't think they would be able to dictate the tempo or completely nullify a side like City or Liverpool, they've had troubles with teams who play quick passing football in the past, I just think United made it very easy for them to maintain a grip on the game, and Ole did little to change that. You can boil it all down to a quality gap but I just don't think that is the case.
If we played PSG and put in that performance at home against them, I'd be disgusted. Yes they're a better side than us and yes they have better players, but I'd still expect to hurt them and give them a competitive match, they're far from Barcelona in their prime. Liverpool scored 3 goals at home past that defence and were unfortunate not to get more, you mustered a single shot on target!