Sony does not have a very good reputation for surviving bad weather, the Canons seem to have a great reputation.
The 1DX2 is the toughest of the lineup, but the 7D2 May be just as good. Both are as well sealed as you are going to see. personally, my 7D2 has seen everything from +40 to -20, has spent days outside on a hiking trip below freezing, heavy rain, freezing fog, and lots of time in a canoe.
The later ones of the 5D series are supposed to be almost as well sealed as The 1DX2 ......
When you want something that works no matter what, you can’t go wrong with a higher end Canon.
As to the R series, way too early to tell, but at some point I am sure that Roger from Lens Rentals will rip one apart and critique it.
Interestingly enough, the Olympus cameras also have a great reputation for weather sealing......
There are plenty of videos up on youtube demonstrating the weather-sealing robustness of canon cameras, at least the higher end. As a tool for the job, I can't be babying my camera. Once, it got so dirty, I washed it in the sink with water and towel. I'm pretty mean to my camera I guess.. haha! Whenever weather gets bad, all of the Sony cameras disappear. The canon Eos R is not up there in terms of weather sealing according to Roger.. I did read his article. Unless the next FF ML canon is super disappointing, I don't see myself purchasing the R: based on all of the things that I already mentioned. I am one of the people here on the forum that is waiting for that epic FF body that can use the amazing RF glasses. Anyone else starting to sell their EF equipment?