For the beginning of the season I followed, Arsenal always performed well. Their habit of entering the half of the season changes unlike the beginning of the season.
If the opportunity is more convincing Arsenal than Manchester United, then it is hesitant to be chosen because Manchester United in welcoming this season we can see that Amorim has been filled by new players with good sharpness during strengthening their respective teams in the previous season.
It could be that the Manchester United vs Arsenal match on Round 1 at Old Trafford is difficult for people to make predictions with difficult analysis levels.
Well, Arsenal have had a similar habit under Arteta. They were a strong and consistent team at the start of the season. Then, their consistency declined towards the middle of the season, then improved again towards the end, when they were already several points off the top spot.

But this time, we won't know for sure whether we'll see the same Arsenal or not. And the same goes for Manchester United. We don't know if Man United will be as bad as last season, or if the team has improved thanks to several new players and Amorim's new strategy. It's certainly difficult to predict every match at the start of the season. So, if we're going to bet, I think it's better to bet on both teams scoring. Because determining which team will win will be quite difficult.