The league phase is going to be underway by September 17 with the first matches. I'm also wondering how this change will feel like. So many things haven't still changed though but I'm only interested in the league phase. Maybe this would help some different teams become more successful in some way. 
My favourite for this season is going to be Real Madrid especially after signing Mbappe.
A lot of teams are adapting with new players to try to unite the team with a short time to get points early in the domestic league and all teams that pass to the UCL will definitely also pursue their plans to quickly get contributions from new players and create a high stability to be able to success in every UCL game. Most football fans would make Madrid a favorite to win the title again and I as a Madrid fan would say the same but a lot of things to consider.My favourite for this season is going to be Real Madrid especially after signing Mbappe.
I mean, although the arrival of Mbappe gives extra strength to the line of attack but we don't know what other teams are going to do that are currently still looking for professional players to be added to the line up. But we also have to look at Dortmund, which is now bringing Guirassy, which could be a threat to Madrid.