thanks for the responses guys, decided I'm going to mix and match willy nilly for my chaos force

including the odd troll on a base here or there too..

One last Q.. don't want to start a new thread for this.. but what are people using for their obliterators? I want to use the OOP imperial robots and use them 1 per base (probably mounted on a 1p piece, given that they're
just a fraction over 20mm in diameter) but as they're classed as infantry, don't want to get caught out by anyone quibbling that there should really be 3 to a base... also, I'm a stickler for sticking to GW only models, not too fond of using third party alternatives.
So.. any thoughts would be much appreciated

Maybe I could pad the stands out with a chaos squat or two as 'minders' or something...