Same as everybody here, depends on when you ask me. White Album has some great songs on it, Blackbird, While My Guitar Gently Weeps, Happiness is a Warm Gun. But there's also a lot of garbage on there. The Beatles were going through their roughest period as a band, so it's mostly just a collection of solo work from the band. Ringo quit for two weeks, and Paul is playing drums on USSR and I think another one too.
Abbey Road is one of those albums that are great to listen to as a whole. Side one, literally any one of those songs could be it's own single. "I Want You (She's So Heavy)" is one of my top 5 Beatles songs. It took me a while, because I hated the abrupt ending, but came to embrace it. Side two is just a great thing to listen to.
As brilliant as Sgt. Pepper is, I'm more of a fan of raw music, as opposed to heavily orchestrated and high production, which is probably why I'm a bigger stones fan. Although that's arguably history's first concept album.
Revolver and Rubber Soul are so similar that I kind of forget which songs go where, but Rubber Soul was the first full Beatles album I owned, and so it holds a special in my heart. That was their first huge breakout from the kiddy pop albums.