People aren't going to like my response, but do yourself a favor and get rid of the Sony, unless you really like it.
I'm in the process of selling my Sony A7R2 system, except for my Voigtlander APO and Zeiss Loxia lenses.
To be fair, Sony has improved colors a lot since the A7R2, however:
With the A7R2 in Capture One Pro, I was using the Canon 1Ds3 color profile, and I was getting at least some "normal" colors. Because without it, the default Sony A7R2 profile was basically YELLOW. Literally, it makes everything YELLOW. The worst color I've ever seen, ever. Meanwhile, a Canon 5DSR and Nikon D850 have some of the nicest color I've ever seen from any camera.
Also, every Sony I've seen renders detail in a "plastic" or "digital" kind of way, and you either see it or you don't. But once you see it, you can't UNSEE it.
I borrowed my friend's A7R4 and used it for a while to make sure that Sony fixed the plastic detail look that I hated so much with my A7R2.
The goal was to make sure that future Sony cameras were going to be good enough that I would feel comfortable buying more Sony FE mount lenses, like the 135 1.8 GM, and maybe some Sigma ART lenses.
However, even at 60MP, the image quality was disappointing *to me*. Nothing had changed. I'm sure many people are happy with the A7R4, but I am not one of them.
I'm currently looking at a D850 system, but also waiting for Canon's new R5, and more RF lenses. Not sure what I will do at the moment.
As a camera, the A7R4 is probably the nicest, easiest camera to use. I mean, the buttons are nice, the auto and manual focusing is stupidly easy, and it's a really nice camera to use. I just feel that other cameras have better image quality.