I have everything GM-ed on 5 characters. I did switch one character from Woodsman to Explorer part-way into it. She lost all the Woodworking and Farming, naturally, but kept the Forestry level.
I went with:
Explorer (Tailor)
Historian (Farmer, Scholar)
Armourer (Metalsmith)
Armsman (Weaponsmith, Woodworker)
Tinker (Jeweler, Cook)
Much easier to GM Metalsmith than before book 14 (uses half the mats now).
Hardest to easiest to GM (more or less):
Metalsmith
Weaponsmith
Woodworker
Tailor
Jeweler
Scholar
Cook
Farmer
Not so easy for Historian to GM Weaponsmithing since they cannot prospect.
Easier for an Explorer to GM Tailor since they can process hides.
Historian<-->Tinker is a good combo for two since you have Farmer for the Cook, and Prospector for the Weaponsmith.