We cannot compare the two leagues in just a few factors but at least in big competitions like champions league or european league.
With this competition we can determine which club from the league is the strongest.
After all, for me in every league there are top clubs or the best clubs like the Premier League has Manchester city and LaLiga has Barcelona.
So we don't need to compare between the main league and LaLiga because these two leagues have the same strength.
If it is necessary to compare, of course I have to say Manchester city is better than Barcelona if only for the achievements they made last season. Because Manchester city managed to get three trophies last season, while Barcelona only got one, namely in La Liga. So in my opinion the comparison is very striking and even very unbalanced. But on the other hand, I also hope that both of them can do better next season, especially in the Champions League.
Maybe the right comparison is for now, but overall of course Barcelona is still above Manchester City. Barcelona faced financial difficulties for quite a long time and this really disrupted the stability of the club as a whole so that their performances at domestic and in European tournaments became quite bad and managed to get up last season even though only domestically but that was quite appreciated. If Barcelona have the same finances as Manchester City then Barcelona will always be a team to be reckoned with in European competition, because that means they will never get obstacle when it comes to bringing in players.
In the new season at Laliga, Barcelona will again get strong competition because rivals Real Madrid understand what failed last season, and of course, it will be a heating season because mistakes made by one of them will benefit their competitors, and it looks like Laliga is back will be domination for Barcelona and Real Madrid.