The F2 & F3. Mostly F2. Why? You know why......I was a bit surprised by this. I just conducted a search here, seeing if there's been a recent thread specifically on favorite 35s, and didn't run across one going back for a year. So, heck, I figured I'd start one. I'm always curious about what people consider to be the best and why. But I guess I should go first.
Currently I own a Nikon F2 with a decent assortment of lenses, plus an EOS Elan IIe, with a few zooms. I like both these cameras. I really like my old F2 -- a lot. But I gotta admit that my all-time favorite is Canon's original F-1 -- specifically the F-1n. Why? Many reasons. I like the fact that it is a system camera. I prefer match-needle metering. Its partial metering pattern makes for easy and correct metering, even in difficultly lit situations. It has mirror lock-up. And the ones I owned were utterly reliable. A close second to the F-1 would be the Nikon F2. Like the F-1, it's a system camera with a mirror-up capability, but no F2 models offered match needle metering. Its motor-drive option was superior to that for the F-1, but the F2's meters are more tempermental and prone to wearing out. I solved that problem with mine by installing the non-metered DE-1 finder. It's a close call, I'll admit.
Admittedly, the quality of available optics will influence one's preferences. When I was shooting Canon FD, I was quite happy with the quality of my photos, and cannot honestly say that the quality of the photos from the Nikkors I own now is any better.
Other 35mm cameras that I've owned and liked a lot enough such that they deserve an honorable mention have been the Canon FTb, Nikon F3, FM and FM2n, FE and FE2, Pentax KX, Olympus OM2, and, of course, the Leica M3. And I'm sure I've forgotten other greats.
So, which is your favorite, and why?