Nikon 85mm 1.4G auto focus speed
Thanks to everyone who responded. I don't think AF speed will be an issue since I only want to use it for still subjects. I was rooting for the Sigma because I knew that focus speed would never be an issue but Sigma's have issues of their own which I'm growing tired of namely quality control (or lack thereof) and a color rendition that is never neutral.
I'll buy it and return it if it's really really slow. The only lens that I have ever had that I found AF speed to be an issue was a Tamron 180mm macro and it just can't be as bad as that.