Hahaha, I´m afraid I don´t want to be the deciding factor. I can´t really tell you what I´d do if I were you. I´d probably go with the 5dsr. But in my shoes, knowing how much more I use the sony than the canon, I´d probably not get a new canon in a while. In fact If I didn´t have all the canon glass, I´d currently rather buy an a99II, but that would be insane with all the glass and equipment.
One more note: my Canon Speedlights do work on the A7RII (no TTL of course and the size is awkward), so I guess your twinlite will work too. And regarding the MPE-65mm - I haven´t used it, but in regard to manual focussing, the Sony beats my 5dIII hands down. But the 5dsr is much newer, maybe that changed.
I hope that doesn´t make your decision even more difficult.