My local group has fully switched to The 9th Age. There are some guys picking up Age of Sigmar now that it has rules for playing games, but I'm staying away. I have no interest in that "game".I don't know anyone in my FLGS actively playing AoS, but I never will; I'll try any ruleset that is free, cheap, or that I can borrow; personally, I prefer ones more like WHFB, such as KoW or, for historical, War & Conquest.
In case you are not aware, Mantic released an historical version of Lings of War, and while the way you build an army is different, they use the same core rules so you can even fight a fantasy army with a historical one if you want.
Back to the original Kings of War, you can already try it for free, they have the rules available as a free PDF.
With the free PDF, you are missing :
- fluff and pictures
- the list of magic artefacts(*)
- the free army lists(*) are sample list that are fully playable, but don't include all the units available in the printed rule book
- the full rulebook has 6 scenarios(**), while the free PDF only give the rules for the most basic one : Kill! (get points for kililng units)
Outside of that, they are the complete rules for the game
(*) there is a free and very good army list editor at http://kow2.easyarmy.com/
that include all units and options from both the core rules and the supplements (including artefacts and unique heroes), and when switching to "View" or "PDF" you get all special rules printed at the bottom of the list (incluing the artefacts) so you can try them even without buying the book (but it book is cheap so if you try and like the game you will probably end buying it anyway)
They also made a version for the historical Kings of War : http://kowh.easyarmy.com
(**)note that the tournament tweaks (sort of a soft errata compiled by the official Rule Comitee, designed for tournaments but used by most players) also introduced 2 new free scenarios (search for the PDF of the Clash of Kings tournament, it includes those)