Originally Posted by dnas
Well, I think that you shouldn't spend TOO much money on a lens with these compromises, so if I was choosing, I'd buy the Tamron 18-250mm (the best of the crop in my opinion). And this lens is only around 60% of the price of the Nikon 18-200mm.
Pros and cons...
On an entry level Nikon body, you'd want to keep focus speed in mind (depending on how you plan on using the lens), and the Nikkor 18-200mm has AF-S to help out. The Nikkor is also stabilized, which could come in handy trying to use a lens that dim in lower light (or with the aperture stopped down for more depth of field).
On a Sony body (I'm shooting with the A700 right now), I'd probably get the Tamron 18-250mm (or even better, the Sony version of it) if I were shopping for an all in one lens with that much range, since the focus motor in newer Sony bodies is relatively fast and that Tamron would be stablized on a Sony body. The camera body focus motor is used for this lens in Sony Alpha mount. The Sony 18-250mm is even better (they regeared it for faster focus speed, with less turns of the focus screw from close to infinity compared to the Tamron branded version of it)
But on a Nikon body like the D60 (what I think the OP is using), the Tamron 18-250mm uses a slower focus motor built into the lens (or at least the newer ones do), and you wouldn't get the benefit of stabilization.