EF 35mm f/2 IS is a terrific walk-around on my 6D. I purchased this Canon 35mm instead of the Sigma Art due to its compact size as I was looking for a relatively small lens that I could use in place of my relatively large 24-70 2.8 II. 35mm is a nice general purpose focal length.
I bought my as a refurb for $479 and its an excellent copy. I'm a big fan of Canon refurbs.