"most attentive" is correct and can be used in written English.
It usually means giving very careful attention to something. For example, you could say: "He was the most attentive student in the class."
But for the most part even those male writers who are most attentive to love and sex tend to direct their attention elsewhere — to the face, the body — and to personality only in a loose sense.
Do even the most attentive readers know?
The most attentive readers will call her wise.
Yet even the most attentive mentor cannot match the omnipresence of gangs, or their familial closeness.
Taminko was hooked on crack and, by her own account, not the most attentive parent.
Her husband was one of the kindest, most attentive men I'd seen.
Impressively, among the most attentive of the listeners were toddlers, transfixed.
Carr's verdict: Very solid, fluent speaker, and most attentive to the House.
It's when the audience is most stable, most predictable and most attentive to the advertising.
In reality, they had ensured only that they would get Virginia at its most attentive.
Worriers are likely to be the most thorough workers and the most attentive friends.
