Hi Logan! From the pros and cons that you’ve listed, I think the Rokinon seems better. From my limited experience with lenses, I know that a fixed-focal length lens (no zoom), usually is sharper and has a wider aperture. As to autofocus, from my point of view, if you’re only shooting landscapes, you don’t need it, but you do need autofocus if you’re shooting pretty much anything else.
Might I ask what you are going to be using an ultra-wide for?