Zeppelin's favourite key is E

[McSeven]

I am listening to Rolling Stone podcast with Robert Plant and Alison Krause and Robert states that Jimmy wrote most of the riffs in the Key of E, so he could get more riffs/bottom end out of his guitar.  So does it matter what Key a Guitrist plays.  Like The Stones favour the Key of G.  Both bands had great riffs.  

I wonder if it's really hard to sing around the Key of E over G.  

[ADK-Zeppy]

As a guitarist, I'd say that is a valid statement on Robert's part. Due to the way guitars are tuned up to a standard of e-tuning, many riffs and musicial ideas “lay out” better in the key of E.  Other good keys for making a guitar sound full are A, G, and D.  If a guitar player is looking to come up with heavy riffs in his or her riffs, the key of E would be the one to choose.