Im thinking of buying a new lens for my Nikon D7100, i have a Nikon 35mm F/1.8 and a Sigma 18-250 F/3.5-6.3 since the 18-250 is not that good in low light and 35mm doesn't have zo0m, im thinking of buy Tamron 17-50 F/2.8 but when i try to google, a lot of people said sigma is better and the 17-50 series from both tamron and sigma are "old"?

So question is are they still a good option? or there are better lens out there i should buy instate of 17-50?

Sigma 17-50mm f2.8 os does seem to be the better choice out of those two. Both brands have not been updating this particular zoom. Those brands have been focusing on full frame offerings lately.

You can also take a look at sigma 18-35mm f1.8 art.