Which watch band is most comfortable?

Oh gosh. That's going to be a personal preference. After trying several, the Sport band that came with my watch, another silicon band, a woven metal, and now a woven nylon. All but the first came from Amazon. So far, I like the woven nylon as most comfortable. I think it's because of the infinite adjustment of the loop, so that if fits JUST right.

Try a couple, see what works best for you.

Neal

I use the Apple "Sports Loop" because it uses velcro to keep the band closed, and because it is velcro it is infinitely adjustable. Some days I want it looser than others, and the velcro makes it easy to make small adjustments.

This is the band that came with my Apple Watch Series 4 (because I ordered it with the Sports Loop).

My Wife uses the same velcro style band (only in a different color).

This is of course a personal preference.