I heard that the coloured comics do better as well in Tapas and Webtoon.
For your comic, I'd go with the first style, I can see that your characters rely in a specific colour scheme, it would lose a bit in black and white considering the good quality of your colours. Despite this I like the black and white one as well, but I think it lacks in depth. Have you tried to add at least a layer of greyscale?
Generally speaking, I believe that the tone of the story matters, for example, in my comic, set in the 1890s, I apply a "dirt" texture in order to resemble an old look, and it's in black and white, as the story could be a bit dark in some parts (and also, to be honest, it's faster to make).