There’s a discussion over at the Hoffman forums on the value of the post-Beatles solo efforts.
There is a touch of magic in the Beatles’ work though I am not really a diehard fan. Generally I find the solo albums less satisfactory with a couple of exceptions. The reason I think is to do with yin and yang, a Chinese philosophy of complementary opposites. Exactly how Lennon and McCartney differ is going to be hard to put into words, but it is to to with light and dark, where McCartney is content mainly to stay in the light, and Lennon is driven to explore the dark. In the solo work, McCartney is always in danger of descending to nursery rhyme, while Lennon is always in danger of descending to primal scream. They are better together.
Personally I tend toward introspection so my preference is for Lennon, and in particular Plastic Ono Band I regard as a work of genius, dark though it is. As for McCartney, I love Band on the Run though it is lightweight, and Flowers in the Dirt where Elvis Costello seemed to play Lennon’s role to some extent, giving the music an edge that McCartney’s work often lacks.