Tough to go wrong with the CDs mentioned frequently above (Rubber Soul, Revolver, SPLHCB, Abbey Road, White Album, One). Just different gradations and styles of greatness.
My personal fave is truly an "album" that was never made into a CD. Back in the day, I had a cassette entitled "Hey Jude" with this playlist:
Can't Buy Me Love
I Should've Known Better
Paperback Writer (on most days, my fave Beatles song)
Lady Madona
Hey Jude
Old Brown Shoe
Don't Let Me Down
Rain
The Balad of John and Yoko
Revolution
That's my favorite.
Close to that list is "Beatles: Past Masters Vol II", consisting of
Day Tripper
We Can Work It Out
Paperback Writer
Rain
Lady Madonna
The Inner Light
Hey Jude
Revolution
Get Back
Don't Let Me Down
The Balad of John And Yoko
Old Brown Shoe
Across The Universe
Let It Be
You Know My Name (Look Up The Number)