Which is the toughest football league?

Related questions

1. Which is the toughest soccer league?
2. Which is the most competitive league in Europe?
3. What is UEFA club coefficient?
4. Which league is the most competitive?
5. How is UEFA club coefficient calculated?
6. How does UEFA club ranking work?
7. Which club is the richest?
8. Which soccer league pays the most?
9. What's the most watched football league?
10. What is the highest level of professional soccer?

Tags

1. #priced
2. #highest
3. #refereeing
4. #technical
5. #difficult
6. #which
7. #world
8. #important
9. #premier
10. #league
11. #really
12. #spain
13. #quality
14. #thanks
15. #competitive
16. #mostly
17. #football