Hm, I haven't given a conscious thought to the photographers whose output I like the most as a whole in a while. And being on several photo-sites and just "collecting" (via favorites etc.) images I like kind of makes things fuzzy, so no guarantee of completeness and no absolute ranking, but off the top of my head:
Berenice Abbott
Aleksandr Rodchenko
Hengki Koentjoro
Branden May
