So I'm making progress with my mechanicum army. So far I've 24 thallax, one tech priest, 12 myrmidons and 3 voraxii. I guess I need to have more characters to unlock different more units. But besides that, where to expand? I'm not too fond of models knight and armiger sized models, nor do I particularly like the aesthetics of tracked mechanicum vehicles. Are castellaxii and ursaraxii good choices? Mobile assault troops sound pretty neat to me.