Before I got the R6 I had no immediate plans to upgrade to mirrorless from my 80D, but a number of things happened that made me make the decision.
Loosing a great opportunity due to the sound of a shutter and not being able to look through the viewfinder when videoing. I can honestly say, since getting this camera, I have managed to take images I could never have hoped before. The eye tracking alone is amazing and makes it worthwile, not just for following a subject but it means you can frame the subject with ease. The silent shutter lets you get close to subjects like mammals without them being disturbed or even know you're there. The image of the Hare shows both of these advantages.
Other advantages include being able to see and change everything via the view finder, the button customisation, the camera works flawlessly with EF lenses using the adaptor and, one of the most unexpected advantages is outstanding low noise the R6 has. The second image below was taken at 25600 with some noise reduction.
As mentioned, the eye tracking is amazing, it just seems to lock onto the subject, effortlessly and in a way no camera I've had below even comes close to.
It's not a perfect camera and I'm sure for some, the 20 Megapixels will seem not enough, but the few disadvantages are hugely out weighed by the advantages.