This is an impossible item to select and it clearly changes with mood and memories.
On the White Album "Yer Blues" is a favorite. One of my least favorite Revolution No9.
So many great songs. I could easily pick others. "While my guitar gently sleep" is always high on the list but so are many of the early love songs. I tend to have a fondness for Lennon's song's but love many McCartney and Harrison compositions also.
Difficult decision!!
In doing this I was thinking of GAD's comments of watching "Get Back" and essentially growing up after the Beatles kicked it off. I was in 3 or 4th grade and grew up with the Beatles and came of age as they went through their maturing phases. That was an experiance that I don't think can be replicated by any other band or generation. It was just one period of history where things all came together. Post WWII kids, technology expansion, turmoil in politics and civil rights and a outspoken generation coming of age.
The Beatles were part of a significant period of many of us growing up.
M