Hello keyworks, and welcome to the Camera Labs forum.
You can read Gordon's take on the Sigma 18-200mm here
and a review of the 17-70mm there
I personally would not recommend to by a zoom reaching 200mm without image stabilization (IS) be it Nikon's VR or Sigma's OS.
The Sigma 18-200mm OS was reviewed here
. But the Nikon 18-200mm VR seems to be the best of the bunch so far...
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
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