02-11-2015, 08:08 AM
The reason to buy a fast wide angle is to need it wide open - and for that the Sigma looks slightly more promising than the others. Not matter how much aberration in total the Sigma delivers: the competition will get problems to sell their steeply priced glass. Again, good to have choices. I just don't see it as such an improvement that I'd "need" to sell the Nikon, but who knows?