To provide a summary of my own favourite aspects of the game-
Practicality-Quite simply, the Rules
work, both in the sense of the armies being amazingly well balanced, and in the sense of being a clear, precise rules set with very little ambiguity. This is as much about what it doesn't have as it is about what it has, namely rules that the game doesn't need, but add unnecessary awkwardness for the sake of character. It also doesn't have rules like True LOS that are very easy to write, and simple in principle, but horribly difficult to implement on the tabletop.
This means I can concentrate on the tactical aspect of a game, rather than on trying to keep a tangled mess of rules straight.
Scenarios- There are six different basic scenarios, and none of them have *exactly* the same scoring conditions. Also, five out of six contain elements of objective or area control, so it's rare for a game to be just about killing your opponents. The different objectives really add a lot of variety to the game, and I always feel a little disappointed when I end up with boring old 'Kill'.
Effective management of timed games- Every tournament game, and the vast majority of casual games, have a time limit on them. Kings of War takes this into account and manages it, partly with streamlined rules that keep games fast to play, but also through allowing the use of chess clocks to make each player personally responsible for playing his own moves within an agreed time frame. This has two important benefits-
Firstly, you are at least not being limited to a draw, or even losing games, because you're opponent wasn't playing fast enough to finish the last few turns.
Secondly, and perhaps more importantly, a solid reminder of the time limit trains players to play faster, and keeps them playing faster.
'If you play too slowly, you lose' is, for me, both fairer and a much better incentive to play faster than 'If you play too slowly, you still have a chance to draw or win by being ahead on VPs mid-game.'
The clocks are optional, but it's an important option to have, especially in a tournament setting, and I personally always use one.
Flexibility in list building- Because, the game is so well balanced, I can play with strongly themed or quirky lists without compromising my competetiveness too far. Lists can be characterful *and* powerful on the tabletop. That's not too say that all lists are equal, quite, but neither am I having to choose between playing the sort of army I want to play and having a chance of winning against the top lists. Again, there's more focus on tactics in using a list effectively.
My dwarves get killer badgers and Earth elementals- Oops, wrong forum.

Well, Salamanders have Fire Drakes and Ember Sprites, and even pirates. They aren't your familiar WFB lizardmen, but neither are they WFB Lizardmen with elements removed, they've got a few fun units of their own to play with.