Yellow seems to be the color of choice. Is this personal preference or does it increase visibility?

From : Don Stackhouse

Yellow is next to white in brightness (good for visibility against dark backgrounds), but has better contrast than white against white clouds and light gray overcast. Besides, it just looks good.

You should pick a color that's easy for you to see. I know some folks who have an easier time seeing lime green, for example. In general you should pick a bright color for visibility against dark backgrounds (such as trees in the background on final approach), and a contrasting dark color for visibility against a bright background like the sky. In the case of planes like the Chrysalis, the open structure with a light colored transparent covering seems to provide for a good combination of dark and light when lit from behind.

Don Stackhouse @ DJ Aerotech