Following on from another thread I started, I am interested in the views about lense choices. Firstly I dont have a massive budget 4 possibly 500 tops.

has anyone experinced a difference in terms of quality of photo produced by Tamron Vs Sigma Vs Nikkor lenses.

I am looking at the

Nikkor - 18-200 ; 18-300
Sigma 18-250
Tamron 18-270

I already have the Nikkor kit lense 18-55 and a Tamron 70-300...

Just interested in your views on build quality Vs price / image quality differences that you may have experienced over time, and any other thoughts you have on the subject. Do these manufacture their own lenses or have them supplied?

I have a Nikon D3000 and my target photos are basically my kids at play - very active, the reason for the 18-200+ is so I can reduce the number of times I'm swapping the lense when out and about with the kids.
Thanks in advance