Sony Alpha a7R II

“Sony was ahead of the game when it came to mirrorless, after never picking up real steam with DSLRs/DSLTs after aquiring Minolta. In particular, they pioneered full-frame mirrorless. The A7 and A7II were good proof-of-concept cameras that made for great digital backs on manual-focus lenses, introducing a lot of enthusiasts to the format. The A7RII had credible enough AF -- not quite besting contemporary DSLRs, but showing the potential was there. And then we got the A7III and A7RIII, and we were off to the races. Plus, during that progression, they release the a7S with some of the best low-light performance anyone had ever seen for video in a hyrbid-style body. They gave people a lot of reasons to get excited and tinker, and many of those people eventually became pros. And they eventually gave pros tangible advantages over the competing DSLRs that were available at the time. By the time Nikon's and Canon's bodies caught up with Sony's offerings, Sony was already well ahead in mirrorless lens development as well.”