Seriously? The EPL is a farm league that an oil club can win 4 times in a row. Maybe if you compare only the middle of the tournament table, the EPL has a slight advantage, but overall La Liga >> EPL. None of the Premier League clubs outside the top category have won anything in Europe, while clubs like Sevilla, even when on the brink of relegation in La Liga, can win the European Cup. Look at those who won the Europa League - Sevilla, Atalanta, Eintracht, Villarreal, etc. If you go back in history, there will be anyone like Zenit, Porto, CSKA, Shakhtar, but there is not a single non-top club from the EPL.
Although I don’t like the idea of comparing leagues with each other because I feel like it is something that doesn’t have. Definite metrics to been measured or compared, each league has its uniqueness. The Laliga can definitely boost of the European supremacy because of how Real Madrid precisely have dominated the combination and not anyone more, but those this makes the Laliga more competitive than the EPL? It’s definitely not. The EPL has many top teams that it can oozes of competition, I can say categorically that the most anticipated match In the league each season is the El Classico, the usual EPL days there is a traditional top 6 not top 3 like Laliga and this on its own is competition already.
As for the trophies, the year Sevilla scooped those titles they weren’t relegation team as you have clearly stated but they were usually a top four team which always gets dumped out of the Champions league and they compete in the Europa league but at EPL any time you see the traditional top 6 in the Europa league it’s means they are having a bad season, take a look at the two clubs in the semi finals now.
Also if want to bring the likes of Sevilla into discussion for winning Europa then bring the likes of Aston Villa and Nottingham Forest for winning champions league too