Both are brilliant and visionary in their own right. I personally prefer Zeppelin. I think that Page, Plant, & Bonham were the best of their time at their instruments and as a vocalist. They were an all-star band in many ways. As Turnbull pointed out, Zeppelin could play so many styles: blues, Celtic folk, head banging rock, and anything in between. Plus they were a powerful live band. They had much more room for spontaneity as a live act, which I prefer. But I can appreciate those who enjoy hearing a direct reproduction of the recorded song that Floyd often delivered.

Floyd put on live shows built on elaborate staging, lighting, etc. Their music was often a soundtrack to their massive stage production. Nothing wrong with that approach. As a music fan, I go to a performance to get swept up in the power of the songs, not the production of a stage show. Robert Plant's swagger and (sometimes) gravelly delivery were fantastic to see live.

The great thing about both Pink Floyd & Zeppelin was that they existed at a time when they had very little coverage on television. In fact, Zeppelin avoided television exposure like the plague. There was no YouTube, MTV, or other mediums for these bands. So if you wanted to experience seeing these bands, you had to go to a concert. Which made the mystique greater. Which, in turn, made even more people want to go see them.