If I were choosing players for a permanent spot, I think I'd choose Carvalho. If it were just a loan, with what we know about their parent clubs intentions, I'd go Diallo, as it seems there's possibly more chance of making that a permanent in the future. Fabio provides competition for Mav and cover for an 8 (though I'm not as sold on him being an 8 in our system as some on here are) whereas Diallo covers Fats and probably a false 9?
Both would be great, either is fine, neither is no big deal either. Weird one innit?!