PSG is indeed one of the strongest teams in Europe, but not the best team. It's not because they won the Champions League that they are considered the best team in Europe.
PSG can also be said to have had a good moment when their strong competitors experienced a drop in performance last season. You can see what happened to Madrid and Man City last season, which became an advantage for PSG. Ligue 1 is always simple, with PSG dominating.
PSG is considered one of the best teams in Europe right now because of their victory and dominance in the champions League they were the best in that competition that's why they can be considered as one of the strongest and also the best cause when the other teams were struggling they gained more advantage to win the champions League. The club world cup was another place where they dominated though they lost in the finals but it doesn't take away the fact that they appeared stronger than most of the teams in the competition.