I'd certainly rate Frazier and Ali below Whitaker here. Frazier was as good at cutting off the ring as anyone ever, but he didn't have much in terms of moving backwards. Ali had a bit too much a preference to retreat in straight lines to really compare to Whitaker, IMO. At least in a technical sense. His combination of speed and balance was extraordinary, though, and he could punch off his movement as well as Whitaker, which is quite extraordinary for a HW.
I suppose it's about what you want from your fighter. Frazier is a pressure fighter. As you've said he was "as good at cutting of the ring as anyone ever". I agree. He also brought really really fast pressure and provided a genuinely solid base for adapted punches whilst retaining the ability to become mobile in a split second. In short, he had perfect footwork for a pressure fighter. Now I would take perfect pressure-fighting footwork over fancy foot-work from a slickster who crosses his feet and comes off balance on occasion. That's an easy pick for me. But in terms of who looks better or who had more variety, yeah, Whitaker. But that's losing sight of the fact that footwork is a function of punching and defence, IMO. Well it's interesting you make the technical comparison...I'm unsure here...anyway, Whitaker's footwork did not make him lethal. Ali's footwork made him absolutley lethal. It's a pretty straight ahead argument and one that is reasonably easy to toss out if you feel like it, but Ali '67 was hugely mobile whilst near-automatically in "set" mode. Unparalleled possibly at any weight.
Whitaker was also good at cutting the ring off. That together with his ability going backwards makes me favour his footwork of Frazier's. But as a pure pressure fighter very few can compare to Frazier. This may be splitting hairs, but I would rather say that punching and defence is a function of footwork. Ali is always tricky in this kind of comparisons, since he wasn't that text book. But perhaps you could say that the moving back in straight lines that he sometimes did is evened out by Whitaker's crossing of his feet. One could say that Ali's athletecism and not his tecnique was what made his footwork spectacular, and while there's some truth to this I think it's a gross oversimplification. Anyway, you're right that Ali's footwork at his peak made him "lethal", i e nigh impossible to beat. Whitaker perhaps wasn't as dependant on his footwork, but that may be down to him being a more complete fighter rather than his footwork being inferior.
sorry, is hard for me to explain me well here, i speak spanish and put my best effort in English, but to have a debate with someone, in another different language is difficult for me ... i can tell the reasons in spanish if you wish
Napoles is a great shout Pea, i love his footwork it was superb it alowwed him to be smooth. Pep is another good example as Pep always kept his feet the same distance apart and was always very well balanced. Another great 'un in terms of feetwork