I wrap all my rods with silk thread. I do this because silk is finer in diameter than the nylon thread used on most commercial rods today. As a result, it gives you wraps that are smoother & flatter on the rod. To keep the wraps smooth, I also coat them with real varnish as opposed to the heavy epoxy coatings on the mass-produced rods. The silk & the varnish give us a wrap that doesn't add bulk to the the rod & will look almost as if the wrap was painted on the rod. The transition of the thread from the rod shaft over the guide feet is smooth & even. It's how they used to do it until they found cheaper, faster ways.
Now no matter if you wrap a guide with nylon or silk & coat it with either varnish or epoxy, the color of the thread will change under the finish. Sometimes this change in color can be dramatic. What looked like a gold thread on the spool might become a very dark brown under the finish. So you have to make color samples when choosing colors from spools of thread.
You can stop this change of color by treating each wrap on the rod with a color preserver. There are different types of color preserver available & some work better than others. However, this adds another step in the process & adds days to the rod's build time. This is because the preserver has to be applied in multiple coats of different strengths in order to get good results.
With lighter color silk threads, they become slightly transparent under the varnish, allowing you to see the guide feet underneath. This is a traditional, desired effect. Darker thread colors won't have this effect. But if you treat these lighter colors with preserver, this effect is lost. Some folks don't care about that at all, while to some it's extremely important.
Choosing a good wrap color doesn't have to be complicated. If you can't decide, just remember that as long as you stick to conservative colors, you can't go too far wrong. It's about what you want. Like they say, beauty is in the eye of the beholder.