This season, what level cup you play in was determined by quality of your team, not your league level. I'm level 2 for league/champions league but level 4 for cup, so winning the cup would've been worth over $4M for me, winning CL would've been worth less than $3M.

If you are in level 3 cup and level 3 CL I'd guess the CL is the tougher event for you. You can see what cup level you were in by going to, "awards", "history", don't know if it is displayed anywhere else. Not sure how cup level was determined precisely, I think my team was rated about 18 at the start of the season.