Nikkor 18-105, 16-85 or 24-85?

I have been searching for a while now, trying to find a lens that takes really sharp images, and my main use is going to be for portraits. I have a d5200, and i have heard from some people that fx lenses aren't such a good idea for dx body, but i have also heard that 24-85 out-performs all of these. So which one should i go for?

Added (1). When i said that my main use is portraits, i meant MAIN use, not ONLY use! I do shoot other stuff too. In other words, i want to know which lens is an overall better, walk around, everyday lens. Oh and, 18-105 is slightly cheaper than the other too. Is there a Huge Difference between the 18-105 and the other ones?

All lenses for DSLRs can take really sharp images.

If you are unable to take sharp images with your current camera and the lens that came with it, then you are definitely doing something wrong.

One problem may be that you probably have the aperture set too wide - introducing too shallow a depth of field. For sharp images throughout the image, from foreground to infinity, you need to use a narrower aperture like F/11 or f/16 - don't go higher or you will get refraction problems which causes distant objects to appear blurry. For portraits you should be setting the aperture around F/4 - if you set it lower you may be getting too shallow a depth of field.

The other possibility is that the shutter speed is not fast enough to freeze the action, or prevent motion blur, or camera shake. Using a tripod can help prevent camera shake. Increasing the ISO or opening the aperture wider can help you attain faster shutter speeds, or just get more light!

By the way, portraits are best taken with a prime lens, not a zoom. On your camera with it's cropped sensor a fast 50mm prime lens would be ideal.

For razor sharp photos, I go for my only digital lens which is also my only zoom lens. That's the 18-55mm kit lens.

Sharpness is the responsibility of the photographer.