Favorite all time camera - wow, a hard decision as I've owned some great cameras as far as I am concerned. There was my first, a Kodak 135 Pony. Collapse the lens and put it in your pocket. All mechanical and simple. It an extinction meter and the Sunny 16 guide off the Kodak boxes made me lust after making pictures. To this day, no other camera I owned does more while many did less quality wise.
The there is the Minox LX, an artform in of itself. Shooting it required understanding of the limitations of the image size but it was such a wonderful carrying camera for street photography and with the flask indoors. I have many fond memories in the files of some great places I visited. Likewise, the ML had most of the same attributes and maybe for me the best of that style camera - a pocket camera that yielded amazing results. Minox knew how to make glass.I only became turned off of it because of the continuing shutter failures.
The Olympus F series; what can one say about it, a nearly perfect size, glass that was as good as anything at the time, light on the hip with full kit and, reliable as heck. Again it did what it was supposed to, make great shots. Maybe the ultimate travel camera as it is half frame so twice the shots per roll and unobtrusive. On the street, the shutter is quiet and camera is small enough that you wer just not noticed.
Rollieflex, I'll leave it to others to praise. I agree.
Leica CL, in my opinion what the M series should have been size wise. A true successor to the SM Leica bodies as it adheres to the dimensions closer than the M series. It comes closer to the Kodak Pony than any other camera for me as a user.
Bronica ETRS; maybe the best compromise in a camera I could imagine. A long term user that never failed, that allowed me to try different ways to hold and shoot a camera with great results, reduced the need for duplicate systems as it does both FM and 35mm sizes. ONly failing is that as you get older it seems to put on weight.
Exacta VX and the entire Exacta line. A non-conventional layout that offered different views, a good selection of lenses and all the goodies to take technically excellent negatives and transparencies. To me still probably the best of all 35mm SLR systems. Of course being left hand friendly helps this lefty.
None of these limit the ability or quality of the negative or transparency. Each and everyone of them points out the imitation is the eye behind the instrument and pushes for the photographer to improve himself.
I guess though, the favorite though is now nearing the end of its life as Fuji seems to be pulling the plug on the film and the Impossible Project seems to be challenges still. I'm taking of the Polaroid 180 and 195. With the film, from Polaroid it was just so nice to use. A great lens, 1st generation prints not 2nd as the film is a positive, the same as a transparency but look at the print and see the etching on the surface giving it an almost 3rd dimension, depth. While marketed showing it as a hand held, it is really to large except for the grab shots and most pack camera users never really saw how good the Polaroid pack film cameras were. The 180 and 195, being all manual seemed to be used more for the professional to confirm lighting and settings than as a primary camera and missed how good they were. I loved the results from them when using them in the Everglades and traveling elsewhere. Smaller than a 4x5, larger than a MF it bridged the 2 sizes allowing it to be carried as a walk around without having a big box hanging such as a Graphic. Sadly, today they sit unused as finding the film is very difficult.
As to users, the Leica CL is my all time favorite. Every bit a Leica, lens quality rivaling the Rolleiflex and is small enough to be a daily carrier, it overcomes the limitations of the Bronica whoch is weight. I can not imagine not having it by me side.