<p>I'm very late to this one, but wanted to pitch in my $0.02 in favour of the two-Sigma solution. I have much the same photographic tastes as William P - not much into lenses wider than 28 or longer than a 135. I shoot a fair bit of street as well. I don't do any shooting that requires a long lens. My body is a D7100.<br /><br />I recently went all-in on the two Sigmas, trading away a Nikkor 17-55 and 70-200 VR - along with a 20/1.8G, a 35/1.8 DX, an 85/1.8G, a 60/2.8G macro and a D300 body to get these lenses. Basically I went from all Nikkor glass to a totally Sigma solution.<br /><br />The focal ranges are exactly what I like - my favourite film setup was an M7 with a 28-35-50 Tri-Elmar, so the 18-35 Sigma feels like home, with an extra 2+ stops over the T-E, plus autofocus. What's not to like? The 50-100 is the same weight as my 70-200, but I get all that gorgeous separation and higher shutter speeds of the 1.8 aperture. My 85 always seemed to be either too short or too long for whatever I want to shoot, which is borne out by the fact that I shoot the 50-100 mostly at either end of its range.<br /><br />I'm stunned by the quality of this glass. The image quality of these two zooms is like nothing else I've experienced, or even imagined, on DX. I far prefer the IQ to what I was getting from 28/35/50/90 Summicrons on Provia back in the film days.</p>