In my opinion:It’s clearly Manchester City and Arsenal

Manuel Pellegrini may have created a less divisive atmosphere at the training ground, and he might be a jollynice chap who is 'misunderstood' by us 'ever-so-unfair' English football lovers, but the fact remains - City are no better in Europe now than under Roberto Mancini. Manuel Pellegrini is guilty of regression

Nobody does glorious failure in Europe better than Arsene Wenger, the Frenchman makes the same mistakes every year and it is beyond tedious.
Arsene Wenger is at least consistent in falling
short with Arsenal.

Idk