In colour XD cuz its the best

I think black and white is quite effective :)

You may also find it interesting (although this was not an option) to draw/ sketch in black and white while drawing an important object/ entity in color. [Easiest example would be water shaded light blue if one of the characters is drowning, while the character itself would be (of course) black and white.]
It would also keep the reader's attention easier :P