Marvel is basically defined by Spider-Man and Wolverine. Without those two characters, Marvel wouldn't be Marvel by just having Thor, Captain America, Iron Man, or the Hulk. Those four aren't the mainstream juggernauts that Spidey and Wolverine are. It's the sum of Marvel's parts that make them big, while Spidey and Wolverine are the two singular characters that keep the company going.
Marvel is equal to DC when it comes to popular, mainstream characters. DC is defined by Batman and Superman. Like Marvel, DC wouldn't survive with just Green Lantern or Wonder Woman. Both companies are tied for 2 and 2. Before 2008 and 2011, Iron Man and Thor were not popular, and I'd even put forth the brass and say that Iron Man was virtually unknown to the average joe. And I'll also go ahead and claim that Robert Downey Jr. is the Iron Man franchise.
Batman, Superman, Spider-Man, and Wolverine are simply the four most recognized, popular, mainstream superheroes in comics. Nobody tops them. Both companies are tied. So I don't understand the claim that Marvel has more characters or "better" characters. Marvel survives on two characters just like DC does.
The only major difference I see is that DC is more ambitious when it comes to adult-oriented material such as Watchmen, V for Vendetta, and basically everything in the Vertigo line, like Y: The Last Man and Sandman.