#5 Arsenal
Arsenal have been very active and seem to have had a good transfer season. Lucas Torreira adds the defensive cover in midfield which often Arsenal teams lack. Bernd Leno is a good shot stopper and will benefit Arsenal tremendously. Sokratis strengthens the defense and Matteo Guendouzi adds another body in midfield.
Honestly, forming this list is extremely hard as you really do not know what to expect from so many teams. One of them is Arsenal. When Alex Ferguson left Manchester United, the transition phase was hard for United and they struggled for consistency and some might say they still are. It will be interesting to see if Arsenal go through the same issue.
It will be strange to see Arsenal under a new manager, but it could end up benefitting Arsenal. Unai Emery will be looking to make an impact and I consider Arsenal the dark horses of this season. I would have put them higher in this list, but simply for the reason that it is very difficult to make an instant impact in the Premier League, they are where they are.