I think people are enamored with Sony simply because of the sensors. I hate to say it, but a camera system is far more than sensors -- even giving Sony Zeiss for their lenses. Personally, I hate the A7 et al cameras. They are worthless for my style of shooting. The blackout of the viewfinder when shooting is totally unacceptable. And this is why I will never use an EVF. Some people love them. I hate them. I used a friend's A7r for all of 5 minutes while doing a studio shoot recently. God did I hate the camera and it's handling. Ergonomics are awful. The friend just tried the out the latest Sony A7r2 at B&H over the weekend. He said he is so disappointed with the camera's handling, and the fact that the viewfinder blackout hasn't been addressed, that he's seriously thinking of going back to Canon, or perhaps Nikon. (He's been shooting professionally for almost 20-years doing corporate work. For that matter, I've shot professionally, 100% of my income, for almost 40, so I've used a few cameras.)
I'll take the handling of my 1Dx or 5Ds over the Sonys any day. I think they were onto something with the Alpha series (like the A99). I considered buying into that a while back, but now I'm VERY glad I stuck with a mature, comprehensive system like Canon. (The same could be said for Nikon.) Sony reminds me of an ADD kid -- onto a new lens mount before you can say "boo".