I would have suspicions that this is a "joke" thread. Sorry op
The 6D is a better camera than the 5Dii in so many ways: image, weight, focus 5dii has a relatively terrible focus system compared to the current generation of full frame cameras, wifi, gps, frame rate, high iso performance
If you want a wide angle lens for a full frame the 8-15L fish eye is a surprisingly sharp lens that is actually designed to work on full frame canons, and it works with limitations on crop canons cameras as well.
If the op is for real read the digital picture's review on the 6D. Here http://www.the-digital-picture.com/Reviews/Canon-EOS-6D-Digital-SLR-Camera-Review.aspx