I would favour Liston, he was at his best against fighters like Rocky. Marciano would come straight at him.
Liston was a good boxer but he was also a little slower and fought rather conservatively, which is why he didn't do great against movers.
He did beat Eddie Machen, Folley and others but he was better when his opponent stood right in front of him, like Marciano would.
It's true that Frazier, or rather Frazier's management, didn't want a fight with Liston because they felt he was not a favourable match-up and taking a risk against Liston who no one wanted to see in the title picture again didn't make any sense. Can't blame them after the 'show' Liston put on in the rematch against Ali..
A whole lot of other top contenders avoided him also... except Leotis Martin who fought a brilliant fight against a slowened down Liston, ending Liston's dreams of another world title shot. Unfortunately the fight ended Martin's career also.
Nothing good came out of that fight, except the highlight reel KO.
Liston beats up Willi Besmanoff
The slugfest against Cleveland Williams