I've tried using the Sony A7R3 and the A73 recently and I really don't like it. Purely from the fact that it does not allow me to have enough manual control and the ergonomics.. Sheesh, I know ergo ergo ergo.. but it really is a thing for me. I do really like the fact that it is smaller and lighter and I would change systems from DSLR to ML for that reason. I usually hike with gear about 30lbs.. travel with almost 45lbs. The Sonys really just feel and act like a very advanced point and shoot camera IMO. The fantastic algorithms allow the camera to focus on your subject super well as you hold down the shutter. Yes it takes fantastic photos and the eye-AF tracking is simply without any competition. But the other things really hold me back from jumping. Obvious the color science which really really is a thing - super annoying in post!! (from first hand experience) Also, on my particular trip to Iceland, my friend's Sony died from some seawater. Another A73 started acting weird from the inclement weather.. the menu and the screen was flickering and acting up. I kept mine out (5D3) in the elements all day, didn't get it soaked in seawater but - still going strong! weather sealing.. it's also a real thing!!
I don't care much for the non-prograde cameras that aren't FF, because I'm hooked to what canon does for me as a whole. It's like people getting the Panasonic gh5 and saying that it's better than the canon C200. There's a reason why the price difference is high and yet people still go for the latter, at least the people that know what quality means.
Now, have I been enticed to buy canon's new ML offerings? yes, but I just want something to match the basic quality of the mark 3 and be just as reliable as I know and trust my camera to be. With this whole online forum war thing between canon and Sony, meh, I think majority are cliff note keyboard busters made up of inter web reviews and videos.