i don't think there is a very much a dispute that these two characters, Magneto and Doom are by far the 2 most popular and widely revered Marvel villains in the history of the company
who do you consider to be the greater villain..
This is not asking who is more powerful, or who is more intelligent...this is no rumble
but simply who is more iconic, who has been written better, greater character development and has been presented as the better villain