The only person who can answer this question is you. If you can rent, or borrow, or buy (from a place that you can return the camera) a Sony a7 II, that will give you some idea if you like the camera or not. Or just wait until the Sony a7R II is released. If you are used to Canon and an optical viewfinder, then until you try the Sony you won't know if you will like their EVF. I just bought the Sony A7 II a couple weeks ago to compare it with my Canon 6D. In my case, I bought the kit lens (28-70mm) and did not use an adapter for my Canon lenses. I found the kit lens to be sub-par. I found the EVF to be slightly, and distractingly too dark in daylight. This was partially because I realized later that the Sony underexposes most shots by a full stop or so. In daylight conditions, there was not much difference in pics taken with the Sony and my 6D. I did not try any shots with difficult light conditions. Based on the EVF and the lens issue, I returned the camera after a few days for a refund. In the end, the biggest plus for the Sony was not the sensor (yes, the IQ is very good) but the small size. I do not like carrying the 6D with the 24-105mm lens and would prefer a smaller lighter camera. The Sony is that, for sure!
Keep in mind that if you want to use your Canon lenses with a higher-end adapter that you may have no - or slow - AF. Another consideration.