Lee Friedlander likes his Hasselblad Super Wide. William Eggleston uses a Graflex Press camera with a roll film back.
Lee Friedlander might like it, but it is definitely not the camera used for his most noted (and I would argue best) work. That was on 35mm, and from the reflections in some of the pix, my guess is a Leica M, though it could be any rangefinder camera of similar design. I've seen pix of Eggleston with one of the Mamiya Press cameras as well (not sure which model, but it was either a Super 23 or Universal, and not a Standard).
I don't really associate a certain camera with any of my personal favorites. However, when I look at them and think about it, most used Leica Ms or the like (Haas, Friedlander, Winogrand, though Haas used a Leicaflex as well). It is interesting, because I do not favor rangefinders in most cases for my own pix. I guess I kind of associate a Rollei with Avedon, though I don't consider him one of my favorites, and I know he shot 8x10 as well. But for the most part, I don't have much idea exactly what cameras my favorite shooters used.