For me, an ideal midfield three will be one DM, one pass master who dictates play and one creative player who can dribble and link up with the attackers.
Barca under Pep - Busquets, Xavi and Iniesta
Madrid - Casemiro, Kroos and Modric
Bayern (not perfect) - Alonso, Thiago and Vidal
We have one DM and one creative player in Matic and Pogba. But we lack someone who can dictate play but Herrera is defensively better and can get in a few brilliant assists. So our midfield three isn't perfect but it's pretty strong. If we get Veratti, I'd call it perfect.
Many teams which don't have this perfect fix use other formations like 343. But for such a midfield three to work, you need three attackers who have are more goal scorers than creative players. Players who mainly come alive in the final third providing the goal or assists and have excellent movement.