I thaught that they were both good in the 80's, now there both loosing there luster, what with cliff burton's death and iron maidens new singer and all.
Iron Maiden's singer isn't one of those guys who just growls and mumbles unintelligibly into the microphone, you can actually understand what he's saying, plus I like their songs much better, even though Iron Maiden has dabbled in satanic themes, it is just music and nobody should take it to seriously.
Metallica has the most hearable vocals every! Iron Maiden is so stupid! Metallica is so much more successful (Has sold the most albums, other than the beatles).
metallica is very good I like them it is not like ironmaiden and heavy metal I hate metal period well metallica puts more thoughts into their songs too