To expand upon my earlier post;
FR (and Golarion, since it's been mentioned and it has the same problem, IMO) have never been able to grab my attention; they're both way too 'Kitchen sinky' - they have no apparent overridng theme, things are all over the place, everything seems like a pastiche of some real-world culture, so on and so forth. I've only run Golarion when I've done a Paizo AP, and it hasn't ever inspired me beyond the AP. Well, that's not entirely true; Numeria is awesome. But one country out of 40 or 50 something?
Eberron and Dark Sun are both unique in that there was a solid attempt to avoid falling into tropes like 'THIS IS FANTASY EGYPT' (cultural themes of Dark Sun city-states notwithstanding, as those end up being minor flavor-points for the most part anyways). I mean, Eberron is definitely kitchen sinky, but it does it in a way that makes everything distinctly Eberrony, whereas FR and Golarion don't make the stuff FRy or Golariony.
I don't love PoL, but it's generic without being Pasticheland, and it stays interesting. I don't really consider it to be a setting as much as a frame of reference, though.
I guess it comes down to this; even if I know rationally that I couldn't have done the quality work that went into FR and Golarion, I look at them and think "I could have done this at home with an atlas and a fantasy name generator".
All IMO and YMMV, of course.