#3 Alvaro Odriozola
Barcelona has had a problem in the right-back position ever since Dani Alves left in 2016. Nelson Semedo was bought last summer and has been performing well, but there isn't another traditional right-back in the squad; as a result, Sergi Roberto, a natural central midfielder, has been forced to move into the role. Alvaro Odriozola could solve that problem.
With a 35 million Euro release clause which can easily be matched by the La Liga leaders, Odriozola is Spain's go-to right-back, and it's easy to see why. Like a natural defender would, he has superb defending skills, and in addition to that, he has great passing, dribbling, and tons of pace to go down the flank, like a true Barcelona full-back would.
And according to the Express, a number of players want him to join, including Lionel Messi. Odriozola is said to be keen to join the Catalan giants, so all that needs to be done at this point is for Barcelona to pay his release clause.
If he were to join Barca, he might not become the first-choice right-back straight away considering Semedo's skills, but his arrival would mean that Sergi Roberto would be able to move up to midfield, which would be benign to both the club and the player's development.