You said it all by now. If you have the proper money and need a fast AF to sports/wildlife get the 5d Mk3 without thinking it. Beside that the 6d is a great weapon for almost every shooter. Brilliant IQ (same as the 5), lightweight, great built quality and so on. The Wifi is handy sometimes.
I had great doubts when sold the 7d. Used a 5d from a friend and loved it, but for landscape I didn´t see the point of getting it. With the price difference I went for more good glass. I´m so happy with my 6!