Absolutely agree. I started a forum topic on this very subject a few months ago asking who was using the Nikon 14-24 on Canon EOS.
Waiting for Canon to develop, test, manufacture and deliver on a new product is a missed opportunity. I've got the 16-35 and 24TSE II and Zeiss 35mm for landscape, but I really need an ultra wide.
I just returned the new Sigma 12-24 II for Canon. Big mistake on my part, the corners are still soft and un-usable in my opinion. The Samyang 14 is calling me but I need an adapter with a chip for focus confirmation.
What has your research found for UWA? ...besides 14-24?