If discussing the two strongest teams in the Europa League and the two most favorites for the Europa League, Liverpool and Leverkusen would come first. These two teams have been performing consistently since the beginning of the season and have maintained consistent performances till now. With these two teams qualifying for the quarter-finals of the Europa League, Liverpool and Leverkusen will currently be far ahead of the other teams that have qualified in terms of strength and consistent performance. AC Milan is a good team in the Italian league but with the way they are performing it doesn't look like they can do well against Liverpool or Leverkusen in the Europa League. Liverpool were the favorites from the start of the season and they might end the season as favourites.
What you said is true, currently the three teams must be able to beat every opponent to reach the semi-finals, besides Liverpool, Leverkusen of course AC Milan can be our favorite for a team that can reach the semi-finals later, for the match against Roma of course it is not a difficult match in my opinion because so far AC Milan has a good record and performance over Roma in the league, I personally would not deny that Milan's consistent performance in the league will be able to show also in the Europa League at this time.
My view and yours will be a little different, if you look at Milan'. history, Surely you know why Milan has been called a giant team in Europe because of their extraordinary experience in European competitions so far, I think precisely compared to Leverkusen, it seems that AC Milan will be a very strong opponent for Liverpool or Leverkusen If they enter the final later, I personally am quite sure if Milan will be able to meet one of the teams between Liverpool and Leverkusen in the semi-finals and I am quite optimistic to see Milan reach the Europa League final this season.
If we list the first three teams, AC Milan will be placed as the third team, but if the first two teams are kept in the list of favorite teams, then we will definitely consider Liverpool and Leverkusen there without thinking about it. Leverkusen and Liverpool have performed well in their respective leagues and in the Europa League this season and these two teams can be called the successful teams so far. Although these two teams qualify for the Europa League at the same time, either of these two teams will win the Europa League title while the other team will not win the Europa League title. The competition will be tougher if these two teams meet in the semi-finals or finals. Although Leverkusen are Europa League favourites, I expect Liverpool to win the Europa League title this season.