As others have said, there are really only two AF choices (and if you're using a 5D3, why would you consider a non-AF lens?).
For images shown on ordinary computer screens, you will see no difference between the Canon f/1.4 L and the Sigma f/1.4 A. The data worshipers will scream the Sigma is sharper while the professional eyeballers will warn Canon has better bokeh. If your practice involves prints at 16 X 20 or larger, you may want to study such arguments as you might see a slight difference.
Since I would rarely, if ever, print large, I went with the Sigma because it kept $400 more dollars in my wallet at the end of the day. And I've been entirely satisfied.