Stamping and Embossing

I was thinking about this the other day while listening to the British Rubber Soul. On that album, the Beatles seemed to work together really well, with a lot of cooperation in individual songs. Lots of good harmonizing and instrumental fills. And their musical talents had developed enough that they could confidently try little accents and flourishes (Ringo's drumming particularly impressed me).

After Rubber Soul, the post-Beatle personalities started emerging more, and the studio tricks increased. A lot of the great late Beatles music often feels like solo work using the best backup band of all time.

Interested to see how people interpret this question. I guess a good case could be made for Please Please Me (when they put all their collective energy into one historic day of recordings), or Abbey Road (where they put it all together one last time, and created the Sound of the 70s) or even Let It Be (maybe both their best and worst album as a band).