I think we need to understand the state of our defence
The good news
We're signing AWB whose an excellent defender, while Dalot and Lindelof will be 1 year older
The bad news
DDG might be leaving, Matic is one year older and Young is pretty much shot at this level
Now lets have a look at our CBs
Lindelof offers decent defending and some great distribution of the ball but he's not fast
Smalling he's relatively fast, is decent in defence, he's good in air but he's distribution of the ball is crap
Rojo and Jones are pretty average. The former has a decent distribution of the ball but he's not a good defender, the latter is always injured, same as Bailly is
Tuanzebe - he's fast, he's got good distribution of the ball, he's relatively strong but he's not good in air
So now we have a good picture of things
Fast: Smalling and Tuanzebe
Good distribution of the ball: Tuanzebe, Rojo and Lindelof
Good 'traditional' defending: Smalling, Tuanzebe, Jones??? Bailly???
Good air prowess: Smalling
So what we need is an aggressive tall defender whose good in air. As Lindelof/Tuanzebe would probably be his long term partner then he should also be rapid if possible. Finally he must also have decent distribution of the ball like any other modern CB.
Now here's my list
Joachim Andersen - he's tall, he's got great distribution of the ball, he's solid at the back but he's not exactly Bolt
Jonathan Tah - another 6.4ft+ defender. From the little I've seen of him he's more rapid then Andersen but his distribution of the ball isn't as great
Ibrahima Konate - another giant of a defender. He's fast and good in air. He has to work on his distribution of the ball though