In an unintended way, the joke track "Digsy's Dinner". The band said they liked the "This could be the best days of our lives", and it (along with the lyrics' puppy love imagery) can sound as a somewhat warm take on "be here now" anthems.
Then there are "Where Did It All Go Wrong" and "Falling Down".
This performance of "Live Forever", just one month before the band broke up. The absolute anger between the Gallagher brothers is palpable, and even if you didn't know they had (another) fight before the show, hearing the bitterness in Liam's voice (a shadow of its former self) along with seeing Noel break down in tears after the line "Now is not the time to cry", tells you that something is not right with this band. The usually uplifting and fist-pumping guitar solo becomes heartbreaking.
Also: "Slide Away", "Cast No Shadow", and "Don't Look Back In Anger".
The sheer idea of the break-up. These aren't bandmates who have decided to go different ways, they're brothers. Brothers who may never see each other again because there's too much that's gone on between them.