I don't think so either because apart from Arsenal and Barcelona there are also other top opponents in the Europa league this season who are capable of winning, teams like Juventus and even Manchester United will definitely be tough contenders for the trophy but as an Arsenal fan I will be supporting my team to win it in the end which I guess should be understandable lol.
You cannot be counting Barcelona as favourites to win the Europa League when they have not overcome Manchester United that is a big challenge for them. If you want to count favourites, it will.be fine you mention both of them because anyone that won between Manchester United and Barcelona may likely get to the finals of the Europa League for this season. It is unfortunate that the two big teams met early
Both are favourites, but Barcelona and Manchester United must beat each other to go further in the Europa League. The Barcelona vs Manchester United match should have been more exciting in the quarter-finals or final, but the drawing results brought them together earlier than expected.
The odds for Barcelona and Manchester United are still 50:50, it is very difficult to predict who will win this match. I hope Barcelona can beat Manchester United. If Manchester United fall early in the Europa League, they will soon make an overhaul of their squad to achieve their goal for next season of playing in the Champions League.