Personally I'd like the one detailing the organizations of Golarion, e.g. something between Cloak & Dagger and Factol's Manifesto. Especially more on the Red Mantis, the Coils of Ydersius, the Harbringers, the Norns and the Riftwardens. Some new ones based on philosophies like diabolism.
Of the lands, first Jalmeray, then the Mwangi Expanses, the Realm of the Mammoth Lords or the Linnorm Kings.
I particularly liked how Korvosa, Xin-Shalast, Sandpoint, Riddleport and Darkmoon Vale were done.
And gnomes.