Quite a short poll, it's like saying "Name the best looking game and why is it Lionheart/Agony?".
Well, "other" then. Wrath of the Demon struck me the most of all Amiga games, as bad as the gameplay is. The only thing I can fault it on graphically is that some enemy sprites in the walking sections look like they belong in a different game. Ask me again next week and I might have a different answer
