Ok, so I just got my Tokina 11-16 today and I was pleasantly surprised (borderline shocked) at the build quality and more importantly the IQ. (Light Artisan will testify!) I really hadn't expected this from a 3rd party lens manufacturer. I'm planning on selling the 18-105 and picking up something faster and with a bit better IQ. I was originally looking into getting a used Nikkor 17-55 f/2.8 (although a bit expensive even used) but having received this Tokina today really has me strongly considering a third party lens for the standard zoom. So the question is, are there any third party lenses out there that have the build and IQ in the f/2.8 range. I've seen some from Sigma, Tamron, and Tokina but I dont really have an idea of their build or image quality. Any help or tips would be great. The gap I'll be trying to fill will be 16-70 on a crop body. If I'm left with a small gap after the replacement, I think I'd rather it be on the 70mm end. Thanks in advance.