Currently, I'm using Golarion for my son's campaign. It was his pick, however, not mine. I had no objections, of course, it's a great setting.
I'm also running a campaign set in the Kingdoms of Kalamar using the Conan rules.
I like Golarion b/c Paizo produces top-shelf fluff to go along with their top-shelf crunch. Golarion gets a lot of things right.
That said, if Golarion didn't exist but the Pathfinder RPG did, I'd still be playing/running the Pathfinder RPG.
In my 20+ years of RPGing, rules & setting are frequently divorced from each other. In the past I have:
Run a Rolemaster campaign in both the Greyhawk and Birthright settings.
Run a GURPS campaign in the Star Drive setting.
Run a GURPS campaign in the Kingdoms of Kalamar setting.
I buy setting stuff to alleviate GM work, for inspiration, and for the entertainment of reading them. I buy rules for running my games.