Chaos Legion Warband formation question

Got myself a Legions supplement book recently, and all in all pretty happy with it. However I do have a couple concerns about the warband core formation that most all the legions have access to in their special formation detachments. First off I am stumped with what to do with the mandatory elites and fast attack slots without sinking a butt load of points into them for redundancy purposes. In the elites slot a single termicide unit doesn't really appeal to me nor does spending a bunch of points on chosen, or possessed. As for the fast attack slot it seems like a waste to use raptors or warp talons since I want to run a raptor talon as my auxiliary choice anyway, and bikes get expensive real quick. So I guess my question is this how do you guys like to fill out your warbands and why? Please include which legion your using. Thank you.