@agtra
Personally I prefer the Japanese flag because it was the easiest flag to draw/paint. When I was young, the art teachers would constantly ask us to draw/color our country's flag. As I am a Malaysian, I will use the malaysian flag for example.
Eight equally thick lines beside a blue square with alternating red and white colors, followed by six more lines below the square. Inside the blue square is a crescent moon and a "star" with 14 spikes. So we all need to get a piece of paper, measure the fk out of everything, count+draw 14 spiky thing, and then color everything. (I pity those that need to draw all the american stars. Feels like a pain.)
Japan? Just one red circle in the middle of a white paper! Don't even need to color the white parts!
(Second favorite is the bangladesh flag, which swaps Japan's white with green.)