Curiously enough, I like Beatles for Sale, even though it's often cited as their weakest album.
Like their very first album, it contains a fair number of numbers they didn't write, and I think it worked. It was also almost the last time they did any authentic rhythm and blues.
Abbey Road with the montage of 'She Came In Through The Bathroom Window', 'Polythene Pam' , 'Carry That Weight' etc and fittingly, 'The End'. Absolutely Brilliant.
The Beatles - the first album, perhaps, to have a personality rather than a mood. You can kind of imagine, if one person had made it as a solo album, the sort of person they'd be. Ironically it's arguably a better concept album than Sgt. Pepper...about someone having a complete mental breakdown just before bedtime.