I used CZ 16-80 and I own Sony 18-55, Sony 16-50, Tamron 17-50 and Sony 16-105.
Sony 16-50 has the advantage of being better in video due to its silent AF motor but apart from that IMO Tamron 17-50 is on par with it in every other thing and moreover its cheaper and lighter. So if AF sound in video is not a concern, I wouldn't suggest spending more on Sony 16-50, Tamron 17-50 should make you as happy. I did a lot of comparisons with them. Eg.
Sharpness at 17mm: http://www.photoagainstphoto.com/sharpness_584_586.htm
Sharpness at 50mm: http://www.photoagainstphoto.com/sharpness_585_587.htm
Reallife sharpness tests: http://www.photoagainstphoto.com/comparison.php?cid=399http://www.photoagainstphoto.com/compar ... p?cid=1524http://www.photoagainstphoto.com/compar ... p?cid=1393http://www.photoagainstphoto.com/compar ... p?cid=1877
(There are several more just check end of page where it says "Other Sony 16-50 DT F2.8 SAM vs. Tamron 17-50 F/2.8 Comparisons")
As you can see their sharpness are quite close in every focal length and aperture. Tamron is also slightly better in barrel distortion in wide end though:http://www.photoagainstphoto.com/distortion_377_380.htm
Its vignetting on fast apertures is also slightly better.
Bottom line, I'd say if you shoot video go with Sony 16-50. In all other scenarios I'd suggest Tamron 17-50.