If you look at the ISO charts none of those lenses are sharp wide open. The Sigma is "better" until you hit F/4 then Canon and Zeiss are the winners.
Release date doesn't mean anything if you are comparing manufactures, only if you are comparing release dates of lenses from the same manufacture.
I think manual focus vs auto focus is the big point here.

IMO the cheapest lens is the best lens, the Canon.
http://www.the-digital-picture.com/R...mp=0&APIComp=5