Or in my case, Tamron. I'm actually contemplating expanding my lens range to cover wider range focal length. As is I've got 28-75 f/2.8 covered, 24-50 f/4 covered, and the kit lens, which is pretty awful at 18mm.
The Tamron 17-50 f/2.8 sounds to me the best choice, but I was also hoping to find one prime wide that just knocked me out. Considering also the Sony 20mm f/2.8, Sigma 20mm f/1.8, and Sigma 24mm f/1.8.
*edit - also throw the Zeiss 16-80 f/3.5-4.5 in the mix. Though not a strong contender with the weak variable f-stop and the heaviest price.
I've only experienced any use from a sigma lens once, and it was rather unimpressive. Also in light of their focus calibration errors being much more common, I'm a bit uneasy about getting a sigma. Somebody please assure me that I'm just being silly. If I was confident in the Sigma, I would probably give up thought of the Sony - being 1.3 stops slower.
Anyway how about you guys? Any of you upgrading your gear when uncle sam gives you back a bit of that money he borrowed?