1. Sanchez.
2. Darmian.
3. Blind.
4. Jones.
5. Fellaini.
In that order, they are also the only 5 I'd consider getting rid of.
EDIT:
To clarify, I'd get rid of Darmian and Blind because they are the only 2 players left in the squad I regard as "deadwood". Jones is a bit better than deadwood but he just can't be relied on, even as a backup centre half. He is way too mistake prone, he has single handedly potentially cost us several games this season. Fellaini is a good player imo but he doesn't suit the way/style I want United to be playing in the future so I wouldn't give him another contract, he can leave. He's also really starting to piss me off with his antics about getting a new contract and unfounded arrogance and his shit-talking about United (also Jose begging him to stay is not a good look for the club
). As for Sanchez, well for me he so far has proven to be the worst signing United has made under Mourinho. I could talk all day about that but if you want more on that look at my history of posts/comments on the issue...
As for some commonly mentioned players:
Shaw - I'd like us to keep him, I still think he can amount to something at the club. However I wouldn't be distraught if he left. There are 5 players ahead of him though for this though imo.
Rashford (on loan, no option to buy) - If there was any season for him to go out on loan it would've been this season, but I think the ship has sailed now, we've experienced his "second season blues", things should hopefully be on the way up with him from here. Maybe he could go on loan, if he got guarantees about playing, but then we would maybe need to sign another forward for while he was gone. In conclusion, no way.
Romero - Are you on drugs?
Smalling - He, along with Bailly and Rojo, are the only centre backs at the club who have shown they are good enough to be around for the long term, for Rojo and Smalling at the very least as backups to the potential pair of Bailly and someone, maybe Lindelof eventually?
Young - Good squad player, should not even be remotely first choice though next season.