Elton John himself never seems pretentious but Bernie Taupin's lyrics often do - sometimes pretentious in a clever sort of way, but pretentious nonetheless. There is a conflict between Elton's and Bernie's personal styles, no doubt about it.
Sly Stone doesn't make good albums: only good records. His style is so infinite and revolves around so many crucial aspects that it has only come together perfectly on a handful of his singles.
Since her landmark 'Tapestry,' Carole King has both oversimplified and over elaborated that masterful album's style until her music has become something more overtly but less effectively personal.