OP...there are a lot of things that go into my camera decisions. Ergonomics and performance are the main things. Back in the 70's I used mainly 4 cams...Nikon F, Leica M3, Hassy SWC and a 4x5 Toyo View. I got rid of the 4 x 5 after a year or so, just did not fit my style of work. When times were tough I had to sell a lot of my gear to live. My last 35mm got stolen and I replaced it with a new $99 Pentax K1000 body and a used $25 lens. This was back in the 1980's.
The Pentax produced fine and continued to use it for decades.
Shot with the Pentax K1000 and 50mm - 1982
In 2018, most digital cams will produce decent photots. 35mm neg film equals to about 3 or 4 mp with a P&S, so everything we got on the market in digital is way above that. The problem with modern cams is they are very complex. We used to only worry about focus, shutter and aperture. Nowadays there are a zillion menu choices. For some reason the engineers decided to screw up the cam with a program dial. And some are even worse with having to use the menu to adjust shutter speeds.
I need easy to carry, compact cameras that can be adjusted without looking at them, just count the clicks...how many of them are like that nowadays?
The focus has to have manual focus and aperture options. No times for AF issues.
You can do it with a Leica, but I didn't use a Leica to shoot this shot below, I used a Fuji that was made 'Leica like' for the red room shot in Amsterdam. It is candid, taken in very low light in a local where photography is illegal. I would have preferred something smaller, like the mini Oly M43, but they are hell to manually adjust on the fly. (I have a book of these shots, so it is not a fluke.)
I also do a lot of circular fisheye work. The cam has to be able to shoot sharp circular fisheye...that leaves the Fuji out.
I do lot of shots from the hip, the camera has to be able to be shot with one hand easily, no AF lag whether IR flash or not. Much of what I shoot is in the dark or low light. EASY zone focus ability is a must.
Infrared flash photo
If you are shooting landscapes and posed work where you can take your time, then almost any cam will do. All I can say is gear is of the utmost importance for what I shoot.
But it goes way beyond gear. If gear was the answer, the richest photogs would should the best shots...but they don't. The gear is like using the right paint and brushes, they don't make the artist, they just allow the artist to create properly.
Here is the bottom line with gear...
If the gear can do it, but you can't...it is your fault.
If you can do it, but the gear can't...it is the gears fault.