Which Noise reduction is better in camera or software?

I have a nikon d5100 and there's an option for noise reduction from low to high. I was wondering if I should turn it off and use software to reduce noise or is the in camera better.

In software. If you shoot RAW, that is. If you only shoot JPG, use the in-camera NR.

I prefer to do it in photoshop. The reason is i can see the image at a decent size first

Don't do it in the camera. Once it's done you can't undo it. Doing it in the software gives you more options and settings.

It's best to shoot in RAW and postpone what decisions you can until you get into Lightroom or Photoshop. You have absolute control of the noise-reduction parameters at that point and can rethink a setting if it smears your image too much.