Well, "In My Life" is an obvious choice. "I'm Only Sleeping" is an interesting suggestion. According to Philip Norman's book John Lennon: The Life, when John was a teenager living with Aunt Mimi and Uncle George, he asked Aunt Mimi what it was like to be dead.
She took him to a nearby cemetery where there was the grave of a woman named Eleanor Rigby. At the bottom of the tombstone was the word "Asleep." So Aunt Mimi told John that death was like being asleep.
I see three Revolver songs coming out of that. (Yeah, I know "Eleanor Rigby" was Paul's. But still...)