http://www.nikonchat.com/sigma-18-200mm-nikon/

If I get the Nikon 18-135 mm lens or lens Sigma 18-200mm lens or something else?
i do not want to spend a fortune on a lens, but I also want to take good image quality. It need not be the best picture quailty on the market. While good results in my Nikon D200.
My dad has the lens 18-135mm for Nikon camera and it's great. The pictures I took with it look very professional. I do not know much about cameras and have never heard of Sigma but I know that I would have my dad's Nikon camera instead of him. He always makes me read the manual and learn about the ways of the camera.
Sigma 18-200mm 1:3.5-6.3 OS HSM For Nikon D60