I would probably get a 5DII over the 6D if it was $1,300 vs. $2,000. With the 6D, you will get excellent center point AF sensitivity in low light, one extra stop of usable ISO (6400), and WiFi. With the 5DII, you will get a slightly more robust body and 1/8,000 shutter speed capability. Frankly, the one stop of extra ISO and AF sensitivity are very useful features to me. What is important to you?
Either way, it sounds like you want more that what either camera offers, so view this purchase as a stop gap for another purchase in the future.