My Epic collection will be largely representing a White Scars Quick Reaction Force right around the time of the Horus Heresy. Being the White Scars are very inspired by the ancient Mongolians, I get to avoid painting any 6mm figures and concentrate more on the motorized part of the motorized infantry.
9 Rhino APCs with 4 Land Raider tanks are the backbone of the force. I hope to add a few scout bikes for recon and a Vindicator for direct/indirect fire support. In my head, this should be reminiscent of Blitzkrieg/Stryker Combat Teams-a quick moving, largely self sufficient force capable of both reconnaissance by fire and out-and-out assault.
I think I've given myself a fairly complete little task force, which suits the fluff of the Vth Legion