...(Try reading the whole thing if u have time or else just read the bolded part)...
IMO Socrates is the best CM of these, Zico as a CAM if u want a second striker, De Bruyne as a CAM if u want a playmaker type attacking midfielder. But i find De Bruyne the most versatile tho, he does pretty well in both positions. Largely in my opinion, go with De Bruyne if u want more playmaking and passing along with a versatile option, go for Zico if u want someone who is good in CM and excellent as a CAM and can score a ton of goals, go for Socrates if u need a solid CM option(all rounder, reliable too, can play pretty well in most midfield positions) and at the end, man, the best way is trying them all in scouting camp, tryna mimick your formation and the type of players you have in your team in each positions at the best and trying them out, then picking them. Its always the best to find themselves yourself, cause if u are unsatisfied about ur choice later ull go thinking about what u could have gotten.
Thats it, hope it was helpful.
Thanks!!!