The Beatles began recording solo projects before the group even split up. George Harrison released the soundtrack to Wonderwall in late 1968, almost at the exact same time that John Lennon and Yoko Ono unveiled Two Virgins. Neither release was a commercial juggernaut, but after the Beatles split in 1970 the four members of the band poured themselves into their solo careers, landing many huge hits on the charts.
What is your favorite song by a solo Beatle? Any song they released under their own name qualifies, and that obviously includes Paul McCartney and Wings and any projects Lennon released in collaboration with Yoko and the Plastic Ono Band. Just please only vote once and only for a single song. And don't overlook Ringo: "It Don't Come Easy" and "Photograph" are masterpieces.