A chariot is my next purchase and I'm just painting up some Skullcrushers!

The Banner of Swiftness on the Core seems to be well worth it so far, that extra 2" on the first march was huge and, after having played a game, I certainly don't need any LESS hounds. The flying Demon Prince seems worth it just for the threat and mobility, and to give the world a target that's not my BSB or other important units.