Spider-Man's the most popular. Wolverine has been the most popular X-Men for decades sure but the literal reason there is an exaggerated focus on Wolverine among audiences is because Fox literally put an exaggerated focus on him and made paid next to no attention to the others. There was no "X-Men". It was Wolverine and friends. If Fox actually treated the X-Men with respect then mainstream audiences would actually care about the other characters. You bring up Ironman and he's literally a character that was important in the comics but not overly popular among readers and was nonexistent to mainstream audiences. Then the movies came out and they handled him well. Bam he's a superstar. Cap's a similar case. Guardians were nobodies even to comic fans. The MCU did not have Marvel's big characters and they still succeeded massively in making people care about the characters. Fox had one of Marvel's biggest properties and made people care about less than a handful of characters. They did nearly everyone incredibly dirty. Cyclops, Emma, Jean, Nightcrawler, Kitty, Gambit, Rogue, Storm, Beast, etc should all be superstars.