I don't have much leeway in choosing when to go on long rides, so lately I've been doing my "tour training rides" in the rain. The first time getting caught in the rain was an accident: the forecast said no rain, but it lied - and 13 miles from home the downpour began, "baptising" my Sam Hillborne and teaching me a thing or two about how to make a rainy tour comfortable. Since then I have not really been resisting rain, but enjoying the empty roads and the fresh air it brings.
My old "lobsterman yellow" waterproof windbreaker. If you are horrified by the neon, I will explain that I see touring in the rain as different from transportation cycling. The latter is a relatively short, urban ride for me on an upright bicycle, and I wear my regular clothing. If it is raining, I wear my trenchcoat and that keeps me dry. I turn on my lights and that keeps me visible. For long-distance rides, I feel that this is not enough - because I cycle through rural areas where my bike and I blend into the landscape much more than in the city. When it is raining, I am practically invisible to cars traveling at high speeds, and in the daytime lights are not always sufficient. So I feel safer wearing brightly coloured clothing in this context.
Having observed the visibility of other cyclists, I would say that bright yellow and red look especially striking against the green-gray backdrop of woodsy and countryside areas. Other popular colours - like purple, turquoise, pink and green - not as much, even if they are neon.
My lobsterman windbreaker is falling apart from old age, so I am looking for a new rain jacket that is specifically designed for long-distance cycling: long in the back and form-fitting around the torso to prevent billowing. And I'd like it to be red. Haven't had any luck so far, and most of the ones I've tried in bike stores seemed ill-fitting. But I will keep looking and welcome any suggestions.