As noted, the French had some amazing colour schemes, derived from from disruptive and dazzle camo experiments in WW1. Sadly the bulk of my French tanks are the boring green/brown scheme, although I do have some in more exciting patterns.
Whether any of these fancy paint schemes made the slightest impact on vehicle survivability is a moot point, but they might have made the crews feel better.
They also help us tell which sides our toys are on.
"Mistakes in the initial deployment cannot be rectified" - Helmuth von Moltke