Man City have spent roughly twice net what Arsenal have in the past decade, only teams with comparative spending are Utd/Chelsea (basket cases). Their wage bill is significantly higher too (near double - and that's only what goes through the books) - Pep plays on easy mode, Barca, Bayern and City the best squad on arrival and departure, expectation being another league and an ECL every 2-3 years.
Liverpool's title and European success is all the more impressive given that their net spend is comparative pittance. Give Arteta, Klopp, Unai or any number of other good coaches City and they too would win the league at a canter. As we know it comes with an asterisk in any case.
He's elite no doubt, but best coach in the world, I'm just not sure. Highest profile, absolutely no doubt.
That Arsenal have been able to compete is impressive.