For me:
LB - Joe Bryan. Only saw the Man U game but he was boss. Exactly what we need. He is a Bristol lad so he may want to wait it out until the summer to see if they get promoted, but I'd put in a bid for him with no hesitation. Plan B - I'd take Luke Shaw on loan, as he would be an upgrade over Martina, and see how he does. If he looks good buy him in the summer. For me getting a LB who can get up the pitch will do more for our attack than a CF would.
CF - Tosun appears to be a done deal. I would stop there. We have to have minutes for DCL to keep progressing. He just can't play every single game. Niasse can still be an impact sub IMO.
MF - My preference is for Ross to stay and play a box to box role next to Gana or Beni. I don't like Schnederlin, uptick in form not withstanding. I don't think I'll get my wish though, so I'm not opposed to N'Zonzi or the lad from Nice. Having said that, I think Rooney needs to play there and bringing someone new in just pushes him further upfield, and that clearly doesn't work. Personally I'd give Liam Walsh a go in certain spots as his skill set is exactly what we need if we're going to play two MF deeper. But that doesn't look possible and it might be too much to throw him in now with no game experience to speak of this season.
Whoever we buy needs to be able to keep possession, allowing us to get others up the pitch. Ross was that player, and Davies could be eventually, but he's struggling atm.