Doesn't matter. Marvel won't let there be a winner. It's always a stalemate. In the 70s confrontation, Doom used that gas to hold control of the world and Magneto was the only one free. He and Beast were the only two on earth left to fight Doom. Magneto and Doom were fighting but Doom got cocky and tried to punk out Ghost Rider, he sonned him and took Doom's memory away. The X-Factor Annual thing had them read each other's minds with their devices in Latveria but Magneto pretty much walked away unscathed. They traded threats when Magneto ruled Genosha in Black Panther's book. In House of M, Magneto embarrassed him after Doom's plan to take over backfired.
You get the point. It always turns out to be equal. Doom and Magneto are the crown jewels of villainy in Marvel. They'll always be around in one form or another.
