Canon's 5 series is their bread and butter camera for all purpose photography. The Mark IV is the most versatile of their bodies because of the features they combine, 4 K video, and motion tracking are the features I prefer. Keep in mind the 5 series is NOT the same as the 1 series, and it's prices reflect that. But, the 5 series has been around a long time and reflects Canon's better efforts. The R is the new kid on the block, new lenses also. It will need time to evolve. Mirrorless has a long road to travel before going head-to-head with what is tried and tested. If you want to experiment go with the "R" series and have fun, new lenses and all. Expect changes along the way. For plain ol meat and potato shooting stick with what you know. "Family shots"? Interesting concept!

I decided to go with the EOS R over the 5D MK IV and have no regrets at all. I use a 7D MK II for all my sports and wildlife shooting (Airshows / BIF) and absolutely love that camera. I was facing the same dilemma when choosing a FF camera. I'm not a professional photographer so the issues that everyone complained about such as Dual card slots and inferior video didn't matter so much to me. I can say that the EOS R is a fantastic camera. All my lens are "L" type and they adapt to the camera flawlessly. I love the fact that WYSIWYG. The evf and flip screen are extremely crisp and clear. The battery life is definitely better than canon advertises. I have shot 850+ images on one battery. I can go on and on about this camera but you have to decide if it will fit into what and how you intend to use it. I can so that if i had went with the 5D MK IV the learning curve would have been much easier as the 7D MK II & the 5D MK IV are almost identical as far as layout and functionality. It didn't take me very long to get comfortable shooting with the EOS R. I cant wait until the new lens are available. I understand they are outstanding as well. You cant go wrong either way. Good luck with you decision!