In Sicily the first time, I found their flag surprising, with the three legs and a face in the center. Then on the Isle of Man, the legs again, but armored, and no face. So it’s not just tri-color bands that can be copied/altered a bit. Scandinavian flags certainly have a running, recognizable theme, too. Barbados, with that striking black trident inside the yellow band, surrounded by blue on either side (somewhat reminiscent of Ukraine or Sweden?) has always stood out for me. Favorite? Not certain, but it’s memorable. But then, they had a Union Jack within their previous flag, before breaking from Britain.
The stirring Union Jack was almost ubiquitous for a while, appearing in the upper left quadrant of so many other flags, including Canada’s, before the current maple leaf design took hold. Heck, even the Hawaiian flag has it, to this day!
Speaking of U.S. state flags, as a kid, I obtained a coffee can emblazoned with all state flags. I was surprised how many (back then) incorporated a Confederate flag within the design, kind-of like so many Union Jack images on so many other flags. C’mon, indeed! Even more common, however, seemed to be flags with simply a blue background with the state seal in the center - usually a circle enclosing two figures, one person standing on the left and one on the right, with a few more symbols between, and maybe a state motto or a date. The flags on the can were only an inch or so across, so it was hard to see details of the images, but many appeared so similar. Those really did seem to be copies of one another, and little variety for so many states.
The colors of the rings on the Olympic flag were chosen, as most every country has at least one of those colors on its flag. There are only so many colors (if you don’t count an exact shade of red, or blue, or gold, or whatever, and some tried-and-true design elements have been copied or modified on lots of flags. The only flag I don’t like a lot (but I will respect it nevertheless) is an orange one marking a roadside hazard or traffic construction slow zone!