Yup, upgrading from my Nikon 18-105mm f3.5-5.6 to something better!
But is this a good choice?
Any Sigma 17-70mm f2.8-4 Contemporary users?

Woah 4 years? Ain't that the previous version of it?
This Contemporary lens was released around 2-3 years ago.

But still, how would you describe the overall image quality as compared with other lens?
Example the Tamron 17-50mm VC/Non VC, or any other similar lenses?

Sigma has redesigned the 17-70mm 3 times, and the Contemporary version is the forth, if I'm not mistaken.
http://www.sigma-global.com/en/lenses/cas/...y/c_17_70_28_4/

It's a part of how Sigma categorize their recent lenses, like the Art lenses like the 18-35mm F1.8 DC HSM and the Sport lens like the 120-300mm F2.8 DG OS HSM.

The Contemporary lens "Featuring the very latest technology, and combining optical performance with compactness, our high-performance Contemporary line covers a wide range of needs." -Sigma

http://www.sigma-global.com/en/lenses/cas/concept/

bump