The humanoids
From back cover of Avon Books paperback April 1980:

STRANGE BENEFACTORS

From far beyond Earth came a generation of benevolent robots whose sole purpose was to serve man by ending wars and easing his bodily and spiritual ills.  Dr. Clay Forester, brilliant scientist and citizen of the distant future, had been recruited by a band of dissidents to stop the fledgling "brave new world."  But why should he try to kill humanity's only hope for everlasting peace?

A vagabond band of psychic anarchists are determined to defeat the invincible robots.  And Clay Forester must discover the secret of the Humanoids and make an agonizing choice: fight for mankind's freedom to struggle and despair... or yield to the Humanoids' implacable imperative of total peace and pure bliss.
American Science fiction, Fiction, science fiction, general, Extraterrestrial beings, Fiction, Science fiction