[thxbb12]

Indeed, very attractive lens.
Recently, a friend of mine lent me his A7R Mark II and I really didn't like the shooting experience.

Sony's most clever move was to open up their mount protocol.
This is one of the main reasons why there are so many 3rd party alternatives.

Hi Florent,

I purchased A7R III and have been using it for last 3 months. I would say the user experience is not good initially, but after spending some time with the camera and configure the main settings it is alright. I sold all of my Nikon gear and have the Sony now and Oly OM-D m10. Getting used to Sony is about the same as getting used to Oly. Compared to Nikon is different story... Having the alternatives is great, this is the main reason I switched. I use it with Tamy 28-75 and Sigma 14-24 DN, it is fine. There is big selection on accessories too, such as L plates remote releases ... I will be selling the my Oly with 2 lenses as well.

Yeah, maybe, but I'm a bit doubtful.
The thing is that I've been shooting Olympus (I had the E-M1 and E-M10 II) and Panasonic (GM5, GX9), but somehow I like shooting my Fuji much much more. So in the end, I always end up taking my X-T20 over any other body. Only when I need something super mega compact, I take the GM5.
I'll very likely sell all of my MFT gear to only keep the GM5 and a couple of tiny lenses.
I highly suspect that no matter how much I use a Sony A7, I'd always like shooting with the Fuji more.

Is it the ergonomics or the color rendering of the Fuji?

The ergonomics and the simplicity.
The colors don't matter much once you edit the RAW.
The colors are nice though, when I don't want to do any post-processing (I usually shoot RAW+JPG), but that's not the main point for me.