Favorite: Calumet 4 x 5 View with 90, 135, 150, and 210 (not used as often as the other equipment, but leads to a much higher percentage of negatives which I eventually end up printing as personal material).
For times (meetings, conferences, conventions, weddings) when a tripod is impractical or I'm just too lazy to lug the 4 x 5 stuff: Koni-Omega with 58, 90, and 180; Yashica-mat 124G; recently-acquired Fuji 6 x 7 rangefinder which could easily displace the Koni except for lack of interchangeable lenses and backs. Overall, my 120/220 exposures are probably at least several times those in all other formats combined, but most of them are done with other users in mind instead of for myself.
For slides, notetaking, casual work, or situations when I know that one-hour color prints and/or nothing beyond 8 x 10 will be needed: Olympus OM-1 and OM-2000's with 28, 50, 100, 200, and a terrific Kiron 105 macro; several old Mirandas (by far the best design because their front-mounted shutter buttons allow squeezing and not jabbing downward--why doesn't every camera have this design?) which I use now only with 50mm or on a microscope because my old Miranda telephotos have oily diaphragms and don't stop down promptly.
Just for fun: Franka 6 x 9 folder and Seagull 6 x 6/4.5x6 folder.
Just-in-case camera: Canon G-III 35mm rangefinder which isn't far from needing new sealing foam but still gives excellent results.
Wish-I-had-but-can't-justify-buying: Makina 67 or 670!
Some of equipment has been with me for over thirty years; maybe I'll still be using some of it thirty years from now.
Konical