Which lens is better for the Nikon D3100?

The:
Tamron - 70-300mm f/4-5.6 Di LD Macro Lens for Most Nikon DSLR Camera

Tamron - A17 70 mm-300 mm f/4-5.6 Telephoto Zoom Lens for Nikon F

sigma-70-30

Thank-you!

Added (1). Sorry its Sigma 70-300mm*.

None of them. Get a Nikon 55-200 VR.

I agree with the previous person. Buy the Nikkor 55-200 VR or save a little more and get the Nikkor 70-300. The Nikkor lenses would be a better investment.

The two tamrons are like the same, the A17 is the current budget model. There's at least three sigma lenses that are 70-300. The one with APO is the best of these and sligthly better than the tamron.

Do realise that these are dirt cheap lenses. You need to stop down to f8 to get any sharpness. If you don't have a pressing need to go to 300mm then the nikon 55-200 would be a much better buy

Go for Nikon 55-300mm lens is very light weight and handles easily. Even in combination with the camera body you hardly know it's around your neck. Amazon had a great deal on this lens and I opted for it over the 55-200 lens (better reviews). The light weight does make the lens feel "cheap" but it doesn't perform "cheap". I took over 1500 shots using this lens and the results where everything I hoped for. Because of the slow lens speed there are times it wouldn't autofocus. I just turned the autofocus off and manually focused the lens. The pictures came out just great. I think the extra 100 mm is worth the money.