I don't think with Arsenal and Barcelona only are the team have favorite for Europe League winner because still have Juventus back to consistency performance at last six matches, right now Europe League tittle race most competitive for winning the second competition level on European. Honestly, Arsenal have better quite appearance in this season at domestic league and European League but I doubt can consistency because next round of European League begin on February next years.
Many predicting the winner of European League between Barcelona and Arsenal but the problem right now Barcelona have against with United on play off round.
Barcelona, Juventus daArsenal have indeed performed well this season in the domestic league. But, regarding the champions, we must not forget Sevilla. In the history of this club, Sevilla is one of the teams that won the UEL title. Indeed, this is not a measure of Seville's success later. However, if the team manages to get the title, the desire to get it back can certainly increase the motivation of Sevilla players to beat the favorite top team in UEL (Barcelona or arsenal).