For Leverkusen and Liverpool to date are indeed strong candidates to become champions in the Europa League because looking at the quality of players in the club and with the performance they have at this time, the difference is very visible as for other clubat this time Milan and Atalanta are indeed one of the good challenger club especially  they have won quite a landslide in the first leg but for Villarreal and Roma actually I think it's too soon to include them in the list at this time.

The reason is quite simple because they are still not certain to qualify in the play off phase even though they are favorites to win in contrast to Milan and Atalanta. for Roma's first meeting they only won a draw against Feyenoord. Its still fifty-fifty at the end of the day because of the situation we find ourselves in now with De Rosi in the domestic competition they are still quite good but there is still nothing to be proud of in terms of performance so Roma is still hanging in the balance when talking about qualifying and not in the playoff.
But for the Europa League there is a wild hope for me when there is a surprise club just like in the previous 2 seasons like Sevilla last season or Frankfurt in the last 2 season who became champions and that's what I hope in the Europa League.