Many that knew the real Liston, the prime Liston, 59-60, not the passe Liston that Ali beat will tell you that Sonny was a beast and with his famous jab, 84" reach, and chin that took the blows from Cleveland Williams and the underrated boxing ability besides his power would out slug Foreman 1 and 2. Foreman as a young powerful heavyweight and Gold Medal Champion , said sparring with Liston was a learning experience and no matter what he tried, he could not back up Sonny.
A very good question, and already great answers. Like Pancho said, Sonny Liston was George Foreman's idol, and they were very similar in their respective primes. Both fearsome punchers that were very intimidating. However, I think Liston was more skilled. Back and forth fight, reminiscent of Foreman-Lyle in my opinion, only in this case Foreman is Lyle.
Liston TKO 8.
Sonny Liston RTD By 11