Previously, I covered the benefits and a few drawbacks of upgrading from my Canon 5Ds R DSLR to a mirrorless system. I'd like to mention the three camera bodies I'm considering.
1. Canon R5. This system most closely compares to my 5Ds R. It's 45 megapixels compared to 50 - a 10% loss roughly. I do print large and those pixels are valuable. However, the R5 is a newer generation sensor and exceeds the 5Ds R in dynamic range by at least two stops. This will also have the side effect of improving noise in the deep shadows that I usually brighten significantly. This is common with landscape photography as the sky is usually much brighter than the deepest shadow areas of the land. This is even more of an issue when pointed toward a sunrise or sunset.
What's the downside of the R5? Well, other than the cost, it isn't a HUGE upgrade from the 5Ds R, and as mentioned, I'm losing some pixels. Also, it's a new lens mount so I'd have to use an adaptor with my current lenses and slowly acquire the more expensive RF lenses. Of course, this will be the case with all mirrorless systems. None of them will use the Canon EF mount which is being phased out.
2. Canon R?. This is a camera that is only speculated to exist at some point in the future. Possibly next year. It will probably be much higher megapixel sensor - between 70mp and 100mp - and will have similar features as the R5. But when it will come is anyone's guess. I don't know if I can wait!
3. FujiFilm GFX 100s. I've always been interested in Medium Format, but the prices for the digital systems - well into the 10's of thousands - have always been far out of reach. FujiFilm has done something really spectacular and made a Medium Format system which is relatively affordable at $6000'ish when compared to previous Medium Format systems. (Technically it isn't Medium Format - it's actually 33 x 44 mm which fits between Medium Format at 45 x 60 mm and Full Frame at 24 x 36 mm, however it is marketed and sold as a Medium Format camera.)
I've been seriously considering this camera. It is 100 megapixels, twice what I have now. That would cut down on my post processing workload and open up more options with compositions. It also comes with all the benefits of mirrorless and newer sensor tech: In-body stabilization, electronic viewfinder, better dynamic range and noise characteristics, etc.
The downsides? It's more expensive than the R5 (and probably the speculated R?), and the lenses are more expensive and larger/heavier than the RF lenses. (However, I can use my EF lenses with an adaptor, and they seem to work well from what I've read.) Also, the larger sensor means I have less Depth of Field with a given aperture compared to Full Frame which means I'll have to use even smaller apertures and accept some (or more) diffraction or embrace out of focus areas in the foreground and/or backgrounds... or I could focus stack. I occasionally use focus stacking, but it's not something I want to do often as it takes up a lot of processing time and can't be done for most photographs without specialized software.
Also, FujiFilm lenses are lacking in the ultra-wide category and the super telephoto category, both of which I use a lot. As mentioned, I can use my current Canon EF lenses with an adapter this may not be an issue.
So, what is my decision? Well, I thought I settled on waiting on the R?, but there still isn't any concrete word on this mystery camera, if it even exists. Certainly, Canon will come out with a large megapixel camera at some point, but who knows when? And both the R5 and 100s are very appealing to me. I'm not sure I can justify the extra expense of the FujiFilm, but then I think, "You only live once, right?"
I really don't know which way I'll go. Prudent-me says wait for the next R-whatever. Eager-me says get the R5 now. Nothing-but-the-best-me says go big or go home with the GFX 100s. At this point, it's a coin-toss. I'll let you know what I decide. If I ever decide.