There seems to be at least two different styles of adventure: Sandbox which tend to be exploratory wilderness or dungeon style adventures, and Plot driven which include Adventure paths. Most groups probably blend the two styles using more of one and less of the other depending on their preferences.
I think one of the main reason Kingmaker was such a hit was its focus on wilderness exploration which is a bit out of the norm for us. It did have something of a plot but it was so loose and almost outside of the action that if you were not watching for it you would have no idea it was there.
The more traditional Adventure Paths have much stronger and more integrated plots. Rise of the Runelords has probably one of the best as you see more and more cult like activity which moves the story throughout the campaign. And then there is Council of Thieves which I have both played and read through and I still can not explain the meta plot - it is just not very clear.
Part of the reason I do the post game session recap on the blog is so that my players can come back and keep the plot fresh in their minds. Who is this chick that keeps teleporting around and telling us what to do in the name of Cardinal Thorn? Who is Cardinal Thorn and why does he hate Mitrans so much? Is releasing this super plague really such a good idea and why does Asmodeus, a lawful evil deity, want to cause so much death? Who are the other Knots and what are they up to (why does it seem like we are doing most of the work?)
On one hand it is great for a GM. The players all understand that they are on a railroad and just follow the DMs clues (subtle or otherwise) unquestioningly. No one ever really asks the question "Why"? On the other hand its a bit disappointing for the DM. You try and present an interesting plot made with characters who are as three dimensional as possible and no one really pay much attention to it. Everyone just kicks down the door, kills the occupants and takes their stuff.
Anyway, I hope that as the campaign continues, the PCs will get to know some of the NPCs better and establish a bit of a relationship with them. I think the White Raven NPCs worked nicely. Introduced in Book 1, they return in Book2 and act as allies but there was definitly tension between the two groups. The PCs were genuinely pissed off when they were betrayed. Now I just have to get the PCs more familiar with the likes of Sakkarot Fire-Axe, Tiadorra, Barnabus Thrain, and Cardinal Thorn who are all key players in what is to come.
What good is a plot if no one knows what it is?