I often wonder, with what degree Sgt Peppers can be fully credited as being the Ultimate Album of all time (a title which is often embraced throughout the numerous 'greatest Album Polls') Although its a revolution in its own sense (when looking at elements such as design, marketing and effort), the context of the Album is not so sharp.
I think the Sixies feel of Sgt Pepper is a little tiresome, sadly spoiled by the 'colourful commercial parody' that plagues today's compilations and films etc
For me personally, I think other Beatles albums give a 'better' Sixties feel. Not so much better, but more realistic, gritty and exciting. Hard Days Night I feel gives a perception of real working class, with the monochromatic colour scheme as emphasis upon the basic ideals which stem from the Beatles attitude and roots (a sense which obviously does not exsist in the same format)
If we are talking about the 'psychedelic' period of the Sixties, for me, Magical Mystery Tour really unearths the naive, experimental and often dark sense of nature from which Acid-Inspired Idealism spawned from. This can also be attributed to Yellow Submarine (film) in which the Colourful revolution is mixed by bleak and dark animation and glued together by theories which can only be described as puerile.
Sgt Peppers is one of its kind, but I often see it as an album that was saturated by ego,