I pained over this decision as well.....I definitely wanted autofocus..and I found the "range" of Canon's offerings to be quite bizarre. I just didn't see why they did not have a screamingly great, with pro-build quality, moderately-upper price range, 50mm lens for their full-frame cameras. How many years have they had to get this right???
Let me also say...I am NOT a Sigma fan in any way, shape or form....but I did a LOT of reading and researching about the Sigma 50mm f/1.4 (with all the extra letters after the name???)...anyway...according to my research this was going to be my selection....purchased from a reliable retailer with a 30-day return policy so that if I got a bad copy with any of the focusing issues (that I am sure that you are aware of), I could return it no questions asked.
Have to say...this lens is GREAT. The price is right for what it is. It is sharp as a tack slightly off wide open, focuses lightningly fast and has incredible bokeh. This will, without a doubt, be the only Sigma lens I will ever own...I personally think that they nailed this better than Canon. Just my take on it. I have been shooting for over 40years and when I pick up this lens I have a very positive feeling when I go out to shoot with it. It helps me create great images.
Take the leap! LOL! Just my two cents.