The best answer; to quote Dutch "color doesn't matter except when it does."
I've seen far too many times when color did matter. Even changing colors when the bite slowed on a BP to something different resulted in a few more bites. And I've seen times when jig head color mattered.
There are plenty of folks who will disagree. But I won't get stuck on one or two colors and not try something else. As stated above, some days it takes dynamite.
Great point Ken...I would to expand the discussion to include "bait profile", as well. This idea goes back to "match the hatch" prevalent in fly fishing circles forever. Up in the first picture, notice the different bait profiles pictured. Color was the discussion, but the different bait profiles stuck out to me. Yes, sometimes color matters, but not as often as people think. However, bait profile does matter more than people believe. Take me for example, I love the Thermocline lil Fry bait profile, the Constant Pursuit profile. My next favorite "general profile" is the crazy angler slab bandit profile...with the first two profiles, I can catch fish basically anytime fish are present. However, there are a few times each year when another profile will out catch my preferred profiles. Crazy Angler's Craws or lil rascals, Laners frog, Therrmocline slab bug, BG Shadpole, or one of the Beaver tailed offerings.
Now, while color is not critical "until it is", certain colors work better than others more often than most...If you want to figure that out, take your favorite color out fishing for a year, and if you catch fish with it most of the time, it is a good color. For example, Looking for 25 always using the High Noon, Laner always using either White Hot or that green color, Shecrappiekilla using that yellow frog (high Noon)...fishing farmer always using the fishing farmer (blue/chart). These are only a few examples, it is clear that these guys regularly catch good fish and good numbers of fish, as well.
As color goes, I prefer to figure out what color "fish bite faster" on any given day...while you can catch fish most days with your favorite few colors, with a little experimentation you can "dial in" the exact color they prefer AFTER you have dialed in the preferred "bait profile". I start with the Thermocline Black Emerald shiner on unfamiliar water...On familiar water, I use the color that I have already established at the best "all around color" on that lake, then adjust from there.
On the subject of jig head color, I prefer to use unpainted heads most of the time, because fish can see unpainted lead better than any other color at any depth, at least that is what research suggests. However, there are times when a fishes ability to SEE the color is not that important, relative to being able to see eyes, or flash, or a specific shape...Pink, red, chart, purple, gold come to mind...flat eyes, google eyes, red eyes, white eyes seem to be options...overal, the combination of options are endless for those hardy souls willing to "figure it out". Let us not forget "Jighead Profile" here. Ball Head, donkey head, road runner head, flat head, walleye head and my favorite...minnow head, non-collared. Why you ask, because I fish a minnow profile bait (Thermocline Lil Fry and Laners minnow)...while the ball head is predominately sold where ever you buy baits, but you can make your own profile changes with a hammer, side cutters, and file, as necessary...plus you can buy sheets of eyes, should you so desire.
While I am busy expanding on options...I key in on two sayings "KISS" or "Keep It Simple Stupid" and "match the hatch"...Interestingly, research ALSO suggests that the crappie's diet is mostly composed of freshwater shrimp, yet most baits produced mimic minnows, frogs, craw dads, and snakes (mr twister tails). Why, I don't really know...maybe they don't know how to make shrimp or they are too small to sell to the public.
Just some more food for thought....you can look at a persons tackle box and tell a lot about them and their approach to crappie fishing...and how long they have been at it, as well.