#5 I Feel Fine. The opening riff is amazing, the energy, especially in the Shea video represents the touring Beatles at their best.
#4 Don't Let Me Down. Sometime I watch this and wonder if they could've ever had any idea that this would be the last set they played together? To see them smiling and interacting makes me think they didn't. Triumphant and tragic.
#3 Help! To me, the melody starts to mature, a sign that John was growing up. The long hair reminds us that RUBBER SOUL arrived just 4 months after HELP! was released.
#2 Instant Karma! This video hints at the great things he was capable of on his own. Too bad the primal scream therapy hadn't kicked in. Love this video, from BBC's TOP OF THE POPS.
#1 Strawberry Fields Forever. Even without lyrics, the song would remind us that 'nothing is real.' But when Lennon's poetry is applied to the Beatles music on the verge of their SERGEANT PEPPER breakthrough, it's magic on magnetic tape.
Honorable mentions: (Started off as two songs, but the list kept growing. Sorry.)
In My Life
Happy Xmas!(War is Over)
A Day in the Life
Whatever Gets You thru the Night
Across the Universe
You've Got to Hide Your Love Away