Liverpool have very strong and experienced team and their coach is experienced too. Leverkusen are rising and making big surprise in this season and they are strong but lack of experience from their coach can be their weakness in knock out matches. AC Milan looks to be good not only with their tradition in Europe but their coach is experienced too.
I agree to put these clubs as best candidates to win Europa League but don't know will they have to meet each other in quarter finals if they go through round of 16.
If I had to bet on just one team, I'd bet on Liverpool as favorites
Even if, as in your example, one of the 3 teams (Liverpool, Leverkusen and Milan) meet in the quarter-finals
But it's not absolute favoritism on the part of the English team, at least in my opinion. Even though Xavi Alonso has less experience as a coach, he has plenty as a player and that could help
To me the classification will be like that:
Classified in boldSparta Prague v
LiverpoolMarseille v
VillarrealRoma v Brighton
Benfica v Rangers
Freiburg v
West HamSporting v Atalanta
AC Milan v Slavia Prague
Qarabag v
Leverkusen