Compared to Leverkusen and Liverpool, Liverpool will definitely be ahead because the English Premier League teams are stronger than the bundesliga teams and Liverpool have performed well against those stronger teams.
I think the two teams, namely Leverkusen and Liverpool, are strong candidates to win the UEFA Europa League. At the moment I can't choose between the two because only two matches have been played. They both have almost the same statistics. So maybe I will wait until all the matches in the group stage are finished and then we can compare the two.
Playing in the Premier League is perceived as an advantage and I think there is some value to that, but when we look at the results of European competitions like the Champions League or Europa League, can we really observe that the Premier League teams have dominated over the last decade?
The last ten Champions League winners were 6x Spain, 3x England and 1x Germany.
The last ten Europa League winners were 7x Spain, 2x England and 1x Germany.
Sure we could compare England and Germany only and there England is indeed still better. But I believe that a game Liverpool against Leverkusen would be close.
Leverkusen and Liverpool will be the toughest opponents of the season and either of these two teams will be champions.