Quote from: danskmacabre;1129928Haven't run PF for many years, but remember being very impressed with the Gamemastery guide.
I used it a LOT.

Gamemastery, APG and Ultimate Campaign while not needed are very helpful for a DM.

All the Bestiaries, Monster Codex and the Ultimate Equipment book was very handy.

Even though I do not care of their world setting, the world books were good.