Hmmm.....I would be hard pressed to pick my favorite Beatles tune, for there are so many.
Even the songs pre-February 1964 kick ass, contrary to what some posters here have opined. Listen to "I saw her standing there" and "Twist and shout" for examples.
I pretty much crank up every Beatles song when it comes up on the radio, for some strange reason, they aren't played to death on the normal "classic rock" radio stations, both on the internet and in Montana. Maybe the royalty payments to ASCAP/BMI are too high, even at this date?
A few favorites, in no particular order:
"I Feel Fine" - the first use of feedback, which would later define Ted Nugent's career
"Happiness is a warm gun" - all time hunting camp favorite
"Within You Without You" - all time smoking a fattie favorite.
"She's Leaving Home" - Paul's best ballad
"A day in the life" - Ringo's best drumming
Dang.....I could go on and on.