I've written a few times about checklist engineering. It's popular with electronics companies such as Sony and Samsung. It's generally popular with car companies like Chevrolet, Hyundai, and Honda. It's about building devices with the personality of a toaster.
For the longest time, great cameras were designed by photographers. A company would look at what worked for a person who didn't just snap photos, but wanted the camera to work each time, every time with consistency.
I never found rangefinders to be this kind of camera but people adored them. Although the old medium format viewfinders were rather odd with the upside-down image (so were twin lens reflex), looking down from the top of the camera, you were engaged in the process. Your imagination worked with reality.
Then, with the SLR, imagination wasn't quite as necessary. You could see almost how the final image would be, as you looked through the lens with which the image would be captured. Then, if you used the correct film and processed it well, you'd end up with an image that came close to your vision, your imagination of the scene.
Today, cameras are easy. You don't have to think at all. Auto-this, Auto-that are available. You can even set the camera to take photos at intervals and just leave the camera doing its own thing, so you don't have to be bothered.
What camera engages you? What equipment says "come out, and let's hear and see and find a story to re-tell people."?
For me, the Fujica series of 135 format SLRs from FujiFilm and the OM-series from Olympus were those kinds of equipment. The Olympus E-1 was another, more specific, more modern model, and certainly now, the FujiFilm X-T1 seems to pull at me that same way, even though I've yet to buy one.
Intuitive controls are important and the camera body has to feel like an extension of the arm (for me, at least). That sort of design doesn't come by starting by specifying internal components and working toward the outside eventually.
Look at the Sony A7/A7R duo. They might as well be called "The Committee" because that's who designed them. There was so little thought to the exterior that a 10 year old could have done it (with Lego?). It's a brilliant combination of parts inside but who but Sony fanatics will want to use it?
The FujiFilm X-T1 has the controls all over it, much like the Fujica ST801 that was so dear, or the Olympus OM-1, if they had been designed for the digital age. When the controls are where you want them to be and you don't have to access a display to make changes, you can be part of the process.
What I photograph with sports doesn't happen twice. There are no second chances. The camera body and lens have to work with me at all times. I don't need to go back to a photo and find that my nose touched the rear display (Why Olympus with the E-M1 and FujiFilm with the X-T1 think I want those displays out in the open, I don't know. The E-1 display was out in the open but it was off most of the time and had no touch capabilities.) I keep the rear display hidden usually. I don't need to find that a dial moves too easily, either.
The Nikon Df was made for people who care about such things, though I don't think it's for me. I've had enough experience with heavy, slippery Nikon equipment from way back when. The D800 (and the legendary, mythical D400) is better for me.
I've thought several times about gutting my Olympus E-1 and finding a way to put the Olympus E-5 or Panasonic GH3 equipment into it. The E-5 innards might be a bit overwhelming for it, but the GH3's insides might just fit. Matching the controls would be the problem, since I'm hardly a hardware engineer. Of course, doing video on a 1.8 inch rear display might be a problem, though I rarely mess with video--so far. However, getting photos in an intuitive environment would be wonderful again.
Mind, the Panasonic GH3 isn't a bad camera body. It was my first encounter with an electronic viewfinder and it wasn't a very good encounter and they've re-worked the viewfinder for the GH4. The problem is that it's not intuitive. They seemed to look at the Olympus E-5, miniaturised various aspects of the design, gave it some Canon appeal, and moved a lot of control to the rear display. Given what I've just written, you know that I don't have much love for the Olympus E-5 either.
The E-5 is a great tool. You could use it to pound nails into the wall. Like the E-1, it's possibly one of the strongest camera bodies from any dSLR maker. It ignores intuitive design, unlike the E-1. There is no mode dial, to provide space for a huge top display. What it has over the E-1 is a higher resolution, better balance with larger lenses, and image stabilization but it never feels quite right in my hands.
So, I ask again, what camera engages you to go out to re-tell a story?
Update 2014.02.20: I was in a camera store yesterday talking to a salesperson I've met in the past. I mentioned to him about the camera being an extension of the body and he just didn't get it. I guess people growing up in a world where electronics were everyday devices has changed the thinking. He suggested the Sony A7, but image quality alone isn't everything for me. It has to be a good shooter and the A7 is an ergonomic disaster, as are most of Sony's serious camera bodies, unfortunately. Apparently, the A7 is somewhat of a disaster to use, but is quite great at image quality. Landscape photographers are more likely to take the time, as are rangefinder users, that Sony is giving them.
Update 2014.04.10: I'm not sure exactly why but the FujiFilm X-T1 has become a big hit for the company. I think it's the overwhelming effect of all the dials. Yes, the image quality is quite good, but I'm not sure that's the driving force, as it's much the same inside as the X-E2. Is it a state of mind? The camera body, like the Olympus E-M1 is just a bit small and uncomfortable for me, but with smaller lenses, it would be a great casual body with enough physical controls to delight the best perfectionist.