1. Ultimate Plug-Ins2. Kingdom-Building AP Plug-Ins
3. Far East AP Plug-Ins
And to answer your NEXT question for the Ultimate Plug-Ins, I have 3 proposals:
1. Ultimate Strongholds - Back in 3.0/3.5 the stronghold builders guide book was crazy popular with just about every DM/player I ever encountered. That being said, ultimate campaigns had a nice section dedicated to building but as with everything in that book, the systems were great, yet felt lacking in overall depth/coverage. As such, your ultimate plug-ins have been much appreciated by this DM.
2. Ultimate Factions - I'd like to see more tools to assist DMs/PCs in making their very own factions from thieves guilds, to bardic colleges, to magical academies, to fighting schools, to secret societies, and more. Inner sea combat/magic and occult mysteries have definitely hooked my group in on the faction/organization ruleset, and left us wanting more. So give us a robust tool set for making that happen, and maybe a few plug & play examples ready to throw right into the mix.
3. Ultimate Downtime - Same line of thought here. I'd like a more robust system for setting up and running shops / businesses.
While I'm not sure there would be enough for three separate products, he's pretty much expressed my feelings.