I love Sigma lenses and have never been first brand fanboy, but been very open to third party lenses and accessories.
I already own a lot of glass from Sigma and have more on the wish list, such as the new 35mm f/1.4 Art.
It's not like I need lenses, but man these Sigmas are nice!
Just look at what people are writing about the 50mm f/1.4, also from the Art series. With the rumors talking about a 24mm f/1.4 and an 85mm f/1.4 – and even a 60mm f/2.8 macro - there's enough to add to my list. There's a pretty good chance that these new lenses will surpass most of what's on offer from Nikon and Canon in quality - and sell at lower prices too.