I certainly agree with Fred, that as many folks as you ask, you’ll get different answers. As much I hate admitting it, I use and have used many different colors over the years, some based on the fish I’m targeting, some based on water clarity, and certainly some based on past experiences.
In over 50 years of fishing, I can honestly say, regardless of what, where, when or conditions, the most used and most productive colors for me has been white, chartreuse, and black in some form or another. That being these are the primary color on a fly or lure, but may be combined with another color.
I’ve tried to follow the same general rules as Fred mentioned, with light and water clarity being the main reason I’ll choose a specific color, but then my mind and available color selections get in the way. Add that to the available or predominant forage base, and I’ll stray away from colors I may normally use, like the Electric Chicken Fred mentioned.
Otherwise, I tend to go with form over color, meaning for example use a baitfish form when baitfish seem to be prevalent, or if bass fishing, a frog, when they seem to be keying on them. So, it’s the idea of match the hatch, but not always with a representative color. I’m sure I’ve never seen a bubblegum colored baitfish or worm, but that color has caught me a lot of fish.
I very much like green pumpkin colored plastics, and have caught many bass and Stripers on them, as well as those in the watermelon shades, but not a big fan of green, like in the hunter green color. Don’t use red much either, although have many lures and flies that incorporate red, but not as the base color. Although I do have a few lures, like Rat L traps that are primarily red, and have caught fish on them.
IMO, this all is mostly a confidence issue, even though many years ago, I thought my problem wasn’t confidence in what I used, but confidence in myself. I believe that’s been resolved, so I have no qualms about trying any color, whether for lures or flies. Still goes back to what Fred sa