Greatest Band of All Time?

In your opinion, what band is the greatest of all time?

I'd nominate Metallica, The Who, and Led Zeppelin to start.
Part of me hates putting Zep in there, because Zeppelin wins everything related to 'best ____ of all time'. But the other part of me says 'Well yeah, because they're amazing'.

I also think Guns'n'Roses could be on the list. Appetite for Destruction is one of the greatest albums of all time. There are 4 or 5 songs on that album that within seconds of you playing, almost everyone will know what it is (Welcome to the Jungle, Sweet Child of Mine, Paradise City, and I'm putting Mr. Brownstone and My Michelle in there. Mr. Brownstone is questionable.)

So, who do you think are some of the greatest bands of all time?

I feel like these bands should all be in the Metal category to some extent but whatever-it's here...
So-if we're talking greatest of all time, I've got to throw Iron Maiden into the gauntlet.
I figure if we're trying to figure such a difficult category we should look at what makes them great. So I'll say longevity, is definitely on the side of Maiden, not only have they been active for about 35 years-but they've been consistently active and produced some of rock's memorable music-by far. Granted, not everything was life-altering, it was certainly all epic.

Thoughts..?

AXIS-live the music-AXIS

I can't really decide though the beatles is probably tied with guns and roses/led zeppelin for the top spot