When it comes to Leadership I prefer the book Ultimate Charisma, I recommend checking it out. It turns feats like Leadership and Antagonize into game mechanics everyone can use and in a way that is balanced. Admittingly, this is only for Pathfinder games, but still.
Care to elaborate?
There are about a bazillion 3rd party supplements for Pathfinder. I'd be interested in revisions to Leadership, but without having an idea about what those revisions were, I'm not going to buy it sight unseen.
Way of the Wicked did some interesting things with Leadership, as it was assumed all the PCs would become evil overlords, and Ultimate Campaign has all manner of rules for activities you can put your followers to work on.
What, specifically, draws you to the ideas in Ultimate Charisma?
Here you can find more information about Ultimate Charisma here: Source 6n
Something to note, I have looked through Ultimate Charisma and have to agree it is amazing supplement that really does all it promises. You want Leadership in you game, this is the book you need and it is perfect for Kingmaker. One of the biggest things that draw me to the system is that it fun and actually pretty easy to use.