Hey there,
Before clogging up one of the other topics, I thought to open one for the discussion of all new Mirrorless Cameras out there. I spent quite some time yesterday at Photokina trying them all out (except Pana) and using all native and adapted lenses. I won't say anything on image quality, as that is nearly impossible to judge at dark Photokina halls.
First a point, from where I'm coming from so that it helps to understand some comments. I have used Canon and Nikon DSLRs a lot and tried the sonies a few times. Personally, I shoot a Phase One XF / Arca and Fuji GFX.
Booths at Photokina:
From the big 6 players (Nikon, Canon, Sony, (Panasonic), Leica and Fuji) I personally most liked the dark Canon booth. I liked the layout, the waiting organized waiting area for the camera tryout and a lot of "action shooting" and history present. I think it shows how much Canon spends on good marketing. Compared to that all other were less fascinating. I hate the crowding around a tiny space to try a camera all other manufacturers use. Sony for me was the worst, as at a point 3 of the 7 employers left for a break without replacement. That resulted in huge waiting times.
New Camera and lenses:
Beauty, Fit, Feel and finish.
When it comes to the finish and beauty, nothing comes close to the Leica SL. It just feels solid and very well made. The second spot goes clearly to Canon. The whole finish is much nicer compared to the rest. The lenses feel great and are well balanced. (Except the 28-70) The whole system feels very solid and comes close to the Leica. Nikon, Fuji, and Sony are all similar in their finish less well refined, but well made. Don't get me wrong they are greatly produced but compared to the Canon they "feel" cheaper. The Panasonic mockup and its lenses are by far the ugliest of the bunch. (Perhaps it will be refined till launch)
Now for me the big question was how do they feel in my hand. I have to say, not good at all. None of the FF MRL felt particularly comfortable. For me they all have the same problem as Sony had all along. The Grip is just to short. I wished they would be 1cm higher allowing a better grip. This probably depends a lot on your hands. I'm talking from the experience carrying my XF and GFX for hours over hours when hiking and even though the XF is !heavy! it fits and feels perfectly in my hand. The grip for me is super comfortable. Same goes for the GFX 50s.
The Leica SL has a better grip, but for me it's to "square" at some points and not nice to hold. The Fuji GFX 50r is nice, personally too big for a rangefinder style camera, but I was positively surprised how good it felt in my hands. Don't get me wrong is nothing to carry in your hands all day long as a real grip is missing.
Compactness body and lenses:
Here I love the Nikon idea. The Z7 with the 24-70 f4. The lens feels a little cheap, but honestly, if it has the optical performance I expect it is amazing how small light and compact that combination is. I really love that Nikon is showing what is possible in the "compact" department. The other two lenses feel ok, but not great. Compared to Canon/Sony/Fuji/Leica they feel plasticy and cheap. Once again, they are compact and very light, so if the performance is right, it's a fantastic combination.
Canon R feels great with the RF 24-105mm f/4L IS USM and 35mm. Great finish, small package and well made. The 50 and 28-70, feel also great and are amazing lenses, they just are huge and not what I want from MRL cameras.
The new Sony 24 is great and it's amazing that they can produce such great lenses in such a small package, I sometimes wonder why some lenses from Sony have to be huge and other can be designed very well in a small form factor.
The new Fuji GFX lenses look nice and probably feel like all the existing lenses from Fuji. The new Leica SL Primes feel great and are probably amazing lenses, but they also cost a lot...
Lastly, I want to comment on the limited tests of Autofocus:
I would rank them the following: Sony>Canon>Nikon>Leica>Fuji (Here GFX only)
Sony still feels faster especially on moving subjects and the eye AF is just amazing. I was surprised how fast the Canon was and how well it did with EF lenses. This might be the most interesting aspect, as they were nearly as fast as there new lenses. The Nikon did Ok, but honestly nothing special there. I wouldn't buy it for the AF tracking capabilities.
Now it concludes my first impressions post. I you have any questions just let me know. I might add some more points later.