Hagler, Monzon, Hopkins (Hopkins himself rates Floyd clearly ahead of himself and Hopkins doesn't even like Floyd), Foreman, Dempsey, and Jack Johnson are clearly behind Floyd. Their resumes are clearly inferior to Floyd's. I like Tunney and he has a very impressive resume, but it's hard to rate him above Floyd, especially considering he didn't fight any of the black fighters from his era (which wasn't necessarily the norm; Greb fought the majority of the top black contenders from the same era and he clearly has a better resume than Tunney).
There is an argument for Archie Moore being ahead of him. Robinson is obviously ahead of him, and I'd likely rate R. Leonard ahead of him, as well. Duran, Charles, Armstrong, Pep, B. Leonard, and Greb could all be rated ahead of him, as well. I'd probably have Floyd barely ahead of Ali. He's either low end top 10 or barely outside of the top 10, but the likes of Hagler, Monzon, Hopkins, Foreman, Dempsey, and Johnson definitely don't deserve to be rated above him.