There's so much more to building a great team than collecting great names.
A big reason why Pep is a bit underrated by opposition fans (and even some City fans) is that they think (quite stupidly) that it's easy to win and play great football when you have an expensive squad.
Actually, the better players you have, the more difficult it is to manage them because everyone of them wants to be the star. Pep is probably the only one who could convince superstars to run and press like mad. Klopp prefers to work with underdogs and had never need to convince players like Messi, Xavi, Iniesta, David Silva, KDB...to work hard for the team.