ADITL used to be my favorite, but I think I dig Getting Better better now. Sure the lyrics are slightly iffy in parts, and the vocals are a little rough, but the solid rhythm parts and overall feel of the track transport me. It’s a feel-good ditty.
On preview: what shy guy said 
I’m trying to remember back to when it came out. Unless you were around then, you can’t really understand how different Sgt. Peppers was. The innovation, which even in Revolver was shoved to the end of the record, now was everywhere. “When I’m 64” is the only song resembling a traditional love song. (Lovely Rita is way too odd for a real love song.) And the production was nothing like that heard from major artists.
John’s part of A Day in the Life, btw, was based on newspaper stories. The guy who blew his mind out in the car was a Guinness heir, and there really were holes in Lancashire.
“A Day in the Life” is one of my two favorite songs that mention the Albert Hall. The other is “You Might” by Nik Kershaw.
I can only speak for myself, but for me it comes down to two things:
The grand scope. A few years earlier, this band recorded songs like “I want to hold your hand”. The journey from that to this brooding, surreal, long song with different character POV:s, abstract lyrics and dramatic shifts is pretty awesome. It all comes together.
It’s superbly written, played and produced. John’s singing is terrific. Paul has an inspired moment in the “woke up, fell out bed” bit with great piano playing and a nice bass line. The haunting orchestration is used to great effect.
It’s hard to pinpoint it if you don’t get it, but I think that sums it up for me.
It seems almost unfair the way A Day in the Life totally overshadows all the other really great songs on this album.