A lot of focus in previous posts on the European teams. That only covers half of it. A league is as strong as its bottom teams. My guess is even teams like Burnley would be able to do well in the conference league.
also, it’s not because PSG plays the semi final of the CL that the French league is top class. PSG, Bayern, they walk their respective leagues every year. In Spain, there’s 3 teams (this year is a strange one). In Italy, there a bit more rotation at the top, but never a team that could wint the CL. The PL has the Sky6 that could win the CL if they have a good season, now us and Newcastle are added to that. Chelsea and ManU are in a dip, but still decent teams who could do something in the EL or ECL. So there are more teams competing.
plus the money makes it that a bottom PL team could buy most players in Italy or Spain.