Led Zeppelin has endured much more than the others, but at the time, Cream and the Yardbirds were more respected. People thought Led Zeppelin were more pop than counter culture.
This was true at least in my pledge class, so I vote Cream for them.
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Tau Kappa Epsilon - University of Miami Alumni - http://tke-miami.com/
Jeff Beck is almost underrated in comparison with Eric Clapton and jimmy Page but is equally amazing and ground breaking. Amazing live show. That said, I'll go with Zeppelin because Robert Plant is much better than Rod Stewart.