Perhaps their early songs, but by late 1965 (Rubber Soul) they quickly expanded beyond the typical 3 chord songs that were so popular in those days. As time progressed, a large portion of their music was "undanceable", something unique at the time but also something they could get away with because of their popularity at the time. In terms of content and variety, they were in a league of their own. Some of this credit should be given to George Martin, who helped with the techonology aspect of the sound, and provided some direction in the music itself. The "non-danceable" music era lasted from about 1967 to about 1972, when traditional rock bands became popular again, long after the Beatles broke up.
Sgt Pepper was the most popular (longest run as #1 album). Next was Abbey Road, then the White Album. Part of this is due to the competition from other bands and change in music tastes by the time White Album and later Abbey Road was released. Sgt Pepper did get a lot of hype at the time. By the time the White Album was released, other bands were catching on, with a wider variety of music. The Paul McCartney side of Abbey Road was an interesting medley of songs.
I'm not sure I have a favorite album. Being 57 years old, what I remember most was what seemed like the very short lived era where college students thought that the world was going to make significant changes. This era peaked about the time of Woodstock, and ended with the Kent State shootings. For me I would say that Crosby Stills Nash and Young managed to musically capture that short lived era more than any other band, sort of like a time capsule of a period that only lasted a few months.