For Elves, I would Pick the
Army Deal over the Warhost. For $12, you get the p[rinted rules, an exclusive figure, another regiment, and another troop (actually, 81+2 WM instead of 71+2). I don't see that the mega army is much of a deal unless you plant to get a Elf Lord on Dragon real soon anyway.
For Undead, I'd make the same recommendations. The
Undead Batallion is the best deal. 110 figures for $63.
Other KoW factions, I have no experience.
This is going strictly by what's offered on TWS's site. After dealing with their "supply chain managed" stuff, I'd definitely recommend NOT ordering anything listed as "pre-order" and anything that isn't "regular stock, ships in 1 day". If they don't have it for immediate shipping, they suck and you won't hear from them until you jerk their chain