The Rokinon 12 is a purely manual affair - every aspect - no electronic anything. But at least you can setup the camera to record the focal length in the exif.
I don't think the 14 and the 12 are all that comparable - 2mm is BIG difference when things get really wide. I could easily see owning both and using the 14 for exterior architecture and events and the 12 for dim interiors, landscapes, and astro.
I bought the 12 first because that fit my budget. I'm pretty sure I won't sell it when I get the 14.