You will never find the perfect camera. That being said, the 5d mk II is a great camera. Canon has not yet adopted the EVF because most of the professional photographers love the OVF. You will probably find the 6D much better than the 5D mk II. The high iso performance is much better and focus with live view (even if still contrast af) is better than the 5D. The 5D is a fairly old camera so it is not appropriate to compare it with 2012 designs even if mirrorless.
If you miss the tiltable screen you can use the wi-fi on the 6D and thether it with a tablet or smart phone. Being able to use wireless with a 10" tablet beats the help out of Olympus's screen when it comes to strange shooting angles and touch screen focusing.
If you really want a tiltable screen and fast AF in live view you can look at the new Canon 70D which has the best liveview AF on the market now. But does not have the high iso performance of the 6D (it might still be better than the Olympus).