I don't know if I can explain this correctly but it seems to me that the Beatles and The Eagles music was more perfect than any others. What I mean is, especially when listening to isolated tracks, you may hear one certain guitar sporadically throughout the song, but only a few strums during certain parts of the song. And it repeats when it gets back to that same part/parts. But there may be 3 or 4 different guitar parts like this. It's like the music was written out before hand for each instrument. It's so different from Zep or Cream or many others. Not saying its not as good, just different.