8x10 - Portra 400 NC. Good color and grain is not a problem and because you can use higher shutter speeds, it's great film for the real world (where things move). I have a nice picture of a Norwegian Line ship passing in front of the World Trade Center, which I couldn't have gotten with an any other film.
5x7 - Portra 160 NC. this is my primary format. Great color and excellent reciprocity (a 30 sec exposure is no problem). It's also the only color neg film still available as 5x7 (meaning I don't have to cut down 8x10). It's cheap too, at $3 a sheet.
4x5 - Portra 400 NC. Primarily used with a press camera for people pictures.
6x9 - Fuji NPZ (ASA 800) with a Fuji 690 rangefinder. Excellent film for the speed, though with slightly magenta skin tones. the camera itself is the ultimate Leica killer. Big negative, x snyc at any speed. At $650 used I don't have a qualm taking it on family vacations.