Depends on your generation I guess. I'm personally not much of a fan of Zep. I'm also not much of a fan of what's commercial. I have however seen many live shows and DVD's of live shows in the past including Zep. Love him or hate him, Marilyn Manson puts on one hell of a show as does Slipknot (if you are looking at commercial bands).
For classics, I'm a fan of G n' R. I thought they did as much for the newer generation as Zep did for the generation before it. Nirvana kicked it up a notch after that, but because their career was so short, it was impossible to see if their greatness could carry on.
However, I must say that my preferences of live shows are more along the edge of Deftones, Dropkick Murphys, The Horrors, the Yeah Yeah Yeahs and everything in between, so we do have different tastes
