Further to the greatness of Led Zep... how many bands can boast a CD so perfect as Led Zeppelin IV? Every song on that CD is an absolute rock masterpiece. Not an ounce of filler, like so much of the stuff that comes out today.
And then, after they've reached absolute perfection, they have the gall to come out and release Physical Graffiti a few years later, which is just a sliver away from perfection.
Lots of the other bands 'Greatest Hits' CDs would stuggle to reach the levels of either IV or Physical Graffiti.