The marauders are looking very clean and some of the conversions you are coming out with are top notch.
If I were to critique, I think you start developing some contrast in some of the tones such as the flesh. The lines your getting are really smooth, you just need some extra zing to make those muscles pop
Monsta mentioned painting the rims black earlier too, but I'd be inclined to do them graveyard earth or kommando khaki, just to finish the base off you no, the rims kinda look "just" primered at the minute, and a neutral colour like this will set "finish" the base, without drawing your eye to much, as those colours aren't a big departure from white. Just my though.
Good work bruta