While Arsenal are starting to rise, now they have to compete with Manchester United who are starting to rise as well and could even become their opponents in the European league round later. Indeed, this is something that can be clearly seen and which of the two teams will be able to win the European league title this season. Both Arsenal and Manchester united have had good performances so far in all competitions and as you said, this proves that these two are the strongest candidates so far until the final round.
It is going to be exciting if Arsenal and United meet in the Europa league, maybe in the final or semifinal, two English teams who are doing very well this season and are determined to win trophies, it will be so hard to predict a winner. But before we can talk about either teams meeting, they have to win their round of 16 games, Arsenal are going to face Sporting, and United will face Betis, these are matches that the two English teams are expected to win, but anything can happen in this tournament, but i want the both of them to qualify so that there is a chance of them playing each other.
Indeed, we must first focus on the round of 16 match next week first. I think Sporting is not too difficult an opponent for Arsenal, but I hope Mikel Arteta doesn't underestimate Sporting because for European competitions Sporting can be a serious threat, especially Sporting will host the first leg and for Manchester United even though the first leg will be hosts, I think they will still be able to secure a win against Real Betis later.