I DM in person (AL) pretty often and I really prefer the black and white maps. They are 100% cleaner and easier to sketch out to play. For FG, color maps do look better, but even there some don't look good. It really depends on the artist and their style. Some of the color maps in Storm Kings Thunder came out pretty muddy (I know that they were wroked on hard to be acceptable, they style are not crisp and look worse when zoomed in on).

For Saltmarsh, it is such an old and famous module that I got maps for it ages ago from fan efforts.