I think we should keep him. I wanted him to be sold last season but I am starting to think we should just keep all our CMs. Melo will be better after his first season here i think and Sissoko will hopefully have less injuries. Marchisio is improving constantly and Poulsen did well when he played.
If there is one CM I would want us to sign as the expense of Melo or Sissoko it would be Banega as he offers something we dont have, a good passer/ deep lying play making mid.