What I don't care from from both bands, I REALLY don't care for. There are a few bands that I can truly say that I like almost every single song they ever recorded, but as epic as both of these two bands are and as important as both were to the music industry, I have to say that they both have a slew of stinkers that I really don't like, at all.
Tough to choose as the two really aren't comparable in any way. I guess I have to use some sort of scale to weigh this out and the scale that I'll use is the "borrowing" they both did from their influences and other artists. Beatles borrowed and gave tribute as well as proper credence whereas Zeppelin flat-out stole songs from other artists and didn't give proper credit until they were forced to. So, with that in mind, I'll give my vote to the Beatles.
Well, that and that they were the most influential and important band in history.