I feel really sorry for you Roland, having to decide which 90+ player is surplus to requirements. Must be tough at the top
I doubt (but I might be wrong) that getting rid of one 93-rated player vs a 91-rated one will affect your APR.
I therefore assume (but I might be wrong) that more important to you is having the edge on matchday.
Ergo, if you really want to get rid of one then keep the 91-rated player.