"Of all the places in all the worlds, you choose to accost Doom in his own home... your dare? Fools! The very worst of men know better... Gods know better."-Doctor Doom. Victor Von Doom is easily the most badass villain in all of comics.
Kang the Conqueror. He commands an army of the ages and pulls some awesome firepower from the time stream. He fights honorably though and prefers to win on the battlefield than through trickery using his time travel capabilities.