Pretty casual player here, named my merc unit after a Daft Punk song and one of my favorite in-universe units, the Crescendoll Hawks. My units mimic the CH's colors, favoring a slightly brighter blue top, gray bottom and yellow trim, as the in-game painter allows. I also favor simple weapons groups, not mixing SRMs and LRMs on my designs unless I'm doing something specific.
O really wish you could customize mechs more in line with MW3 personally, because I'd love to stack multiple streak launchers on say the Trebuchet, for a short ranged brawler.