Just to point this out, Pettis has yet to fight any of the Wrestlers/Sambo Guys in the light weight division other than Henderson. He fought Guida, Stephens, Lauzon, and Cerrone before his title shot.
Styles make fights, and until I see Pettis beat guys like Thomson, Melendez, Nurmagomedov, or other grappling based fighters I am unconvinced he is the best in the lightweight division.
as a Man once said "He may be the champion, but I am the Best" I do not believe Pettis is the best in the division, Only champion due to his road to the belt being favorable to him and circumstances.