9) Yaya Toure
Arsenal have needed a midfielder with power and strength ever since Patrick Vieira left and they could have had one of the strongest midfielders around.
Wenger said: “It would be up at the top [of my list of regrets]. He had an agreement with us – and it’s not because we didn’t want to sign him that he went to Ukraine.”
However, passport paperwork denied Toure from joining Arsenal.