One of the strangest elements of any comic book writing is the treatment of villains. Of course villains can be some of the strongest characters in all of comics, but generally speaking the villain has to be written to the hero and not vice versa. In writing the villain to the hero though, certain problems can arise, namely that of power levels. When Lex Luthor is occasionally written as an adversary to Batman, it is rarely Batman agaistn Lex in a superpowered suit, rather it is dark and scary Batman sneaking around and confronting Luthor some place. In rare cases a Batman villain might transfer over to a more powerful hero. In one of my favourite Wonder Woman story arcs ever, the Joker is called in to take her down and he does quite effectively (for a while anyway.) Conversely the Joker versus Superman usually results in the Joker mysteriously having constructed some sort of super powered robot so that he can avoid confronting him directly. Or as another example, most of Green Lantern's enemies are so based on power ring like powers, that it is not as easy to apply them elsewhere. Incidentally this is also what happened to Doctor Light, a quite powerful hero, who was reduced to a sort of joke villain for the Teen Titans. This is just DC though, and I am not sure that the same holds for Marvel. Marvel's villains tend to be of the same general threat level across the board, regardless of hero strength. It is kind of hard to debate that Iron Man is stronger than Spider-Man. Spider-Man himself might generally be considered stronger than Daredevil. However, a Daredevil villain such as Bullseye is still quite a match for Spider-Man, and a Spider-Man villain such as Doctor Octopus (as seen in the recent Fix Me story arc) is still a decent threat to Iron Man. Doctor Doom shows up regularly just about anywhere in Marvel books and generally the hero and him are a decent match. So does this make the lineup of Marvel villains better, and I mean that not on a case-by-case basis but rather as a whole? Well I would say yes, I think DC's villains are more iconic, but Marvel had more of a mixed bag to throw at heroes and to spread around. Part of this is the dynamics partially of what makes DC popular, but at the same time a lot of potentially good stories involving their heroes go untold.