spiderman
Judging by the number of different titles he appears in, Wolverine. Although Spider-Man continues to be a very popular hero as well.
Emma Frost started out as a villain for most of her life but in most Marvel realities she later joins the X-Men and becomes a superhero.
spiderman
batman
There's no real consensus but I'd suspect Spider-Man could be the most "famous".
Batman has the largest for DC & Spider-Man has the largest for Marvel.
ironman
Wolverine is often considered one of Marvel's most unkillable superheroes due to his powerful healing factor, adamantium skeleton, and fighting skills. His ability to rapidly regenerate from even the most devastating injuries makes him extremely difficult to kill.
The most popular superhero movies for kids are Spiderman, Superman and Batman. This movies are accompanied by toys and other merchandise that keeps kids interested in the brand.
Ranking superheroes is subjective, but some of the most popular and powerful Marvel superheroes include characters like Spider-Man, Iron Man, Captain America, and the Hulk. Other popular heroes like Thor, Black Widow, and Doctor Strange also have a strong fan base. Ultimately, the best superhero is a matter of personal preference and what qualities resonate most with individual fans.
In Marvel, the strongest superhero is often considered to be the Hulk due to his limitless strength and regenerative abilities. On the DC side, characters like Superman or the Green Lantern are commonly seen as the most powerful due to their array of abilities such as super strength, flight, and energy projection. Ultimately, the strongest superhero may vary depending on the storyline and context.