To put a spin on a related thread, which film(s) and in which format(s) do you shoot most often?
Starting the ball rolling:
In medium format, when shooting in black and white, I most often shoot PanF Plus; FP4, however, is my "go-to" film during the winter months. For color work in medium format, I currently shoot Ektachrome E100G and, when subject matter warrants, E100VS.
In 35mm, I shoot either Tri-X or HP5 in the Leicas when working in black and white, and E100G when shooting in color. In the Nikons I have, since the discontinuation of my beloved Kodachrome, been shooting both Ektachrome E100G and E100VS in a (approximately) 70/30 ratio.