With R-Type's American cover it appears they didn't want to sell the fact that the game has huge, awesome bosses.
To me, the WORST American cover is Legendary Axe II. The Japanese version at least fits the mood of the game.
The American one . . . the whole, happy little people swinging axes from the groin area probably didn't sell many copies of the game. I actually like that game quite a bit. Every time I pick it up to play, I look at the cover and a small part of my soul is crushed. I'm honestly considering picking up the PC Engine version.