Rei means Zero wrote...
I think what winter tried to say was, that vectors/usage of the pen tool makes thinks look cleaner. You can use it for colouring too, for example to improve your highlighted areas which look too blocky and quite unnatural. Looking at your colouring as it is now, I'd prefer your works being uncoloured. I mean, the lineart is very fine and I like the proportions and usage of perspective, but the colouring reduces the quality and makes them look unpleasant. Don't let this take you down, if I see colour I JUST want to see detailed high-quality shading and texturizing, and if ppl cannot use colouring properly I get kinda angry, especially when the lineart itself looks good.
He got it right. Using pen tool for lineart and coloring is the boss way.