Serie A is a decent league in my opinion. The competition is good. Of course, the English Premier League is the best league in the world right now. La Liga is decent. The problem with La Liga is that the competition is genuinely decreasing day by day. At least the competition for Real Madrid and Barcelona is certainly decreasing. Every season Barcelona and Real Madrid are almost always at the top of the table.
Juventus made problems for Serie A this season, the point deduction of 10 points and more has been a big topic in the media. This leads to no trust and there are players who do not want to play at such a club. Juventus has done even worse in the past: manipulation. Most of the players in Italy are Italians, they want to stay in their home country. You can see that in the national team, almost all of them play in Italy.
Spain and Barcelona or Real Madrid have much more money. I think they also have other chances Tor ein international titels.