Sigma: Amazon.com: Sigma 70-300mm f/4-5.6 DG APO Macro Motorized Telephoto Zoom Lens for Nikon SLR Cameras: Camera & Photo Nikon: Amazon.com: Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR Zoom Nikkor Lens for Nikon Digital SLR Cameras: Electronics I wholeheartedly believe the Nikon would be the better of the two, but the price difference is so large I'm not sure if its "worth it." I normally wouldn't consider getting a 3rd party lens, but in this case its more than double the price for a Nikon. I realize the Sigma doesn't have image stabilization, which is obviously a knock against it. Lets say I'd pay $100 for VR, that still leaves me paying $210 more for the Nikon. My gut tells me it may not technically worth the extra money, but owning a Nikon would feel better and that counts for something. One thing of note is the Sigma has a macro mode which reduces minimum focus by almost two feet, which would come in handy from time to time. In my mind, the zoom capability is the dominating factor in getting "the shot" as opposed to the (usually minor?) differences in lens quality. I took some photos of my girls playing soccer w/my kit 18-55 and none were any good. Keep in mind I said dominating factor; I know other things are important as well. If anyone has either lenses (tried both would be great), let me know what you think.