To me the best-produced album is and always will be Abbey Road. The clarity of the instruments, how they work together... man. Side Two should be required listening for anyone interested in pop music.
And I must disagree with the comment on the first page slamming Strawberry Fields' production. For its time, it was as fresh and surprising as anything. You all probably know this story: John tried it as a rock quartet arrangement, then a strings/keyboard arrangement in a different key and tempo, then ordered George Martin to put them together. And..... somehow the different tempi and keys made it work! And Martin's string arrangements in and of themselves merit praise. (for even wilder strings, listen to Harrison's Within You Without You from Sgt. Pepper).