#3 Alberto Moreno - Liverpool
As an Arsenal fan, i wouldn't be too pessimistic about Alberto Moreno. His time at Liverpool may have been negative, but if anybody can get the best out of him, Unai Emery can.
The two have worked together at Sevilla, and Emery turned Moreno into an Europa League champion. The two enjoyed a healthy working relationship, but everything went downhill after he joined Liverpool.
Moreno is an interesting one, and he's definitely worth a try. Should he continue to be reluctant to sign a new Liverpool deal, Arsenal could even sign him for free. His current deal runs out this summer, so it could either be a very cheap or even free deal.
Moreno is like Bellerin in a sense that he is a lot better going forward than he is at defending. Aged 26, this may be too late to change - but Unai Emery is capable of miracles.