A very subjective and controversial subject with the simple answer of why does it matter? If we try and look for immortality we shall never find it in a physical form.
Why does it matter who is the greatest band of all time shouldn't we be supporting all metal? Surely metal is about the community and everyone has different tastes in music and different genres of metal.
Unlike other genres of music metal is incredible because it has the special power of bringing people together and finding common ground. Yes of course there are some great bands out there but surely we don't want to be stooping to the lowest common denominator just like mainstream music where everything is financially driven.
In my opinion the bands that I support are the greatest bands of all time but of course that won't be everyone's conclusion as everyone has their own ideas.
If we try and single out one band as the greatest then we simply disregard all the other great bands. And of course some bands that are so called "the greatest" are simply over commercialised (not mentioning any names).
Some people will regard the smallest unheard of bands as being the greatest. Why does greatness always have to be linked to success?
If we are driven to debate greatness then we are simply causing division within the metal community? In my opinion all bands can achieve greatness if they adhere to the metal commandments.
1. Thou shalt play metal not just for monetary gain. ( i.e. not f*** off after making millions like One Direction)
2. Thou shalt have metal in their DNA and blood.
3. Thou shalt be awesome.
4. Thou shalt not lip sync or pretend to play guitar.
5. Thou shalt turn up to gigs and not cancel on the night (except emergencies).
6. Thou shalt not be an a****** when fans want autographs photos etc.
If you want the whole list of commandments I'm sure you can find them somewhere on the web lol. This is what makes metal the greatest.