Hi, Vivid, good question / observation.
Actually, #31 has what seems to be the best color scheme (reds in the appropriate places but red-ish flesh colored arms and faces).
#25 and #30 are nearly identical.
#28 seems cleaner somehow..I like that. Also good job matching the fonts, that's important, and the background color is better.
To be honest, I'm torn between #31's example of full coloring (which standing alone is excellent) or something minimalist like #28 (which does need a tweak on the horse and more red stripes etc in the pants of the troops on the rear cover etc...but probably not on the spine).
This may be one of those contests where I can't make up my mind and end up purchasing 2 covers.