advice needed: last trade

[mike_3456]

Need some advice on my last trade. I want to to upgrade one of my mid-range players to a premium for my last trade. What would be the best upgrade? Here's whos on the chopping block:

Puopolo, Gaff, D.Swallow, Max Bailey, Jack Riewoldt, Dion Prestia

(Doesn't matter what position)