I haven't heard any other versions of this song, although I can't imagine anyone else making it their own to extent Ms Simone does. With just a piano and her voice, it's such a beautiful yet majestic song.
The slightly gospel-inflected interpretation by Hathaway on his eponymously titled recording with Roberta Flack in 1972 (Atlantic Records) is simply transcendent. The string arrangements by Arif Mardin wondrous, flute accompaniment by Hubert Laws, as usual, fluid and moving. And the closing moments by Roberta Flack, angelic.
from Roberta Flack & Donny Hathaway (Atlantic 82794-2) available on CD - same as album (same as album)
Recommend your favorite
version of For All We Know