While I personally think that the 1st and 2nd edition covers are the best (and I admit, I may be biased to those editions), I think that the 4th edition cover is one that if you covered up the D&D name I would have thought Dungeons & Dragons the minute that I saw the artwork.
I agree, though it does annoy me that Paladins have to be lawful good. This is the only class that is restricted to good as their alignment, and I have always felt that a paladin could be lawful neutral or lawful evil instead, though the class description may take a little modification.