At the moment, the weakest teams in the Europa League are Midtjylland and Sevilla (quite ironically, the multiple winner of this tournament this season among the outsiders), the rest of the clubs are strong and some pairs are indistinguishable from the pairs in the Champions League (especially in the group stage). It is a pity that this tournament has a secondary status and there is no way to fix it, it greatly affects the atmosphere around the games - it is not as tense as in the Champions League.
The name given to it as a second tier competition in Europe is why people think it isnt a big competition but if look at The caliber of clubs competing in it then it is only juicy and entertaining just like the Uefa Champions League.
The game between Manchester United and Barcelona has always been a game of entertainment and this year wont be an exception. I will be cheering United in this game because all round they have a better team to me compared to Barcelona at the moment