If it was Paul, well let's see - he wrote the iconic bass line, he performed the incredibly avante gard, complex and just all around kick-*ss guitar solo ... how much of this song was actually George's?
I might be off here, but I would venture to say that except for a few exceptions, none of the songs that any of the Beatles wrote were strictly "their songs." What I mean by that is, the Beatles were actually a
band, and even though they each wrote songs, when they played together and worked on the songs they each contributed. I remember reading an interview with George where he talked about his infamous fight with Paul that appeared on the Let It Be movie, where George took offense to Paul's trying to show George how the guitar work should be during "I've Got A Feeling." In the interview, George said something like, "I was the lead guitarist; it was MY job to work out the guitar part of the songs, not Paul's." So I really don't think that when John, Paul, or George wrote a song, that they worked out the guitar riff, the bass line, the drums, and the rhythm and just sort of asked their bandmates to play it that way.
Think about it: Why were none of the Beatles as solo artists able to duplicate the huge success they had as the Beatles? I feel it was simply because they were a band, and each member contributed a little something to make the Beatles so amazing. When they didn't have each other in the recording studio, the sound just didn't come.
That's why I simply can't stand it when people try to argue that George wasn't important to the success of the Beatles, or that Ringo wasn't, or anything along those lines. They truly worked together in a way that can and will never be duplicated.
I guess I just went off on another one of my tangents. At least this time we're not talking about recreational marijuana use!