I mean, every kind of "best of all time" lists is likely to name both The Beatles
and John (which means his solo career).
They act as if he was the only one to contribute to The Beatles's quality of music, often ignoring Paul, Ringo & George.
Let's face it, his solo career was not that memorable or impactful, besides the exception of the song Imagine
And the most iconic thing about him was probably his relationship with Yoko and his untimely death.