That can make it slightly easier to paint the mini. Like using gunmetal silver while priming Necrons, add some nunl oil on it and many would consider the mini done already or at least battlefield ready.

I haven't settled on any specific factions. Started with Techmarine, then some Mechanicus units, then a 1 armiger knight, then just half assembled Grimaldus and retinue and currently assembling Noise marines, hopefully i can finish those by the end of the next week as i am on a vacation so there should be enough time to paint those.