I agree with Neuro. The only non-Canon L-series lens I own is the Sigma 35/1.4 (I have 9 L-series, from 14mm - 600mm). I have not tested them all, but I have read enough tests to be fairly persistent. But the Sigma 33/1.4 can stand up to any of the competitors, regardless of price. I truly hope they will produce other focal lengths with the same quality. That will put pressure on the likes of Canon, Nikon and Zeiss.
I just saw an add today, where the Sigma sells for just over 1/3 of the price of the current Canon L. So if Canon releases a 35 vII, I think we are in for a treat. Sharpness, vignetting (the only weak point of the Sigma), CA etc. will most likely be stunning. Build quality will be great (but so is the Sigma), whereas IS is not something I will miss, but handy if it is there. f1.2 would be cool tough. But having seen Canon“s price policy over the last years, it is very easy to predict that it will be (very) expensive.