Which lens give the best picture quality?

I'm new to slr cameras, and I've recently bought myself a nikon d3100 set from costco. Does anyone know what lens I'll need go get to obtain quality like this picture
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currently I'm using the standard lens it came with it.

You already have one.

You get a good photo with good exposure / lighting, good focusing and good composition.

What you can do is take a photography class. As of now, you are going to be play around with your camera. You will be taught to know how to control your camera and you will be able to take good photos under most, or any condition.

I set the aperture to wide open (at f 2) so the background is out of focus (so it won't distract the main subjects). The subjects were illuminated by the sun light (behind me, we were under the shade of a large tree).

It looks like a simple photo, and it is, but I was in control of the camera and it came out the way I wanted it to.

In no time, you will be having fun with yours too - learn it the right way so you will not have bad habits now.

The lens you have is capable of getting pictures like that and even better. It's not the lens. It's you. In case if you were wondering what lenses are the best in the dSLR world, it's those no-zoom manual-focus-only ones that have the best optical quality.

Too generic of a question.

if you know the following terminologies, than you should know which camera lens (and Accessories) to buy:
- aperture
- DoF
- wide angle
etc

Just buying a camera and clicking the shutter release won't get you "quality pictures"…

learning HOW to use the camera will!

Your kit lens is capable of a shot like that. Just zoom to a wide angle setting, and shoot with aperture wide open in aperture priority mode.

All lenses have strengths and weaknesses. The kit lens isn't that bad if you know how to use it.

You can achieve the same type of image quality (or near enough to make no difference) with the lens you currently have. Great color, contrast… All that has more to do with proper exposure and good light than the lens or camera…

This was shot with a Canon XSi using the kit Canon 18-55… See how crisp it is and how good the colors and contrast are? The picture was not edited (other than minor tweak to white balance and exposure).

Sure, it. Not an amazing photo (my wife actually took this one) but it illustrates the point: It's all about light and understanding the science of photography.

You can gamble with a zeiss F-mount lens (expensive and it may not give you the results you want because much of the quality has to do with the photographer), or you can simply save yourself money and use the lens you have now (don't shake the camera or you will get fuzzy unsharp pictures).