One other issue is to screen for setting/flavor.
Examples of greyhawk-specific PrCs woudl include the Fist of Hextor, the Knight Protectof of the Great Realm, the Ravager (they're dedicated to the WOG deity Erythnull), and to a lesser extend the Warmaster (the background / flavor text is based on Furyondy, a kingdom in the center region of the WOG).
But power-wise ... no, nothing extraordinarily overpowered, and generally it's all "generic" enough to, with slight tweaks, be plopped down almost anywhere.
Duellist, for example, makes fine sense as a common PrC for those from the Waterdeep region (twin-sword rapier-and-dagger style ... fits perfectly, IMO ...). Either the Fists of Hextor or the Ravagers could be re-named/re-worked slightly, to fit in with Bane; Knight Protectors and Cavaliers woudl fit the Western Heartlands, and Cormyr/Sembia, quite well (alongside Cormyr's Purple Dragon Knights, ofc).
The Drunken Master and Master Samurai fit fine in Thesk (or the Shou Expatriate pseudoregion), originating along the Great Golden Way; those two are actually easier to fit into the FR, than into WOG, in fact.