50mm or 35mm Lens for D5300?

I have a Nikon D5300 with 18-140mm Kit Lens.

Now I'm thinking of taking a Prime Lens, have gone through few sites and got to a conclusion that the Prime Lens should be either a 50mm or 35mm.

But here I need you guys help as to which one I need to choose. I have just started photography and which one will be good addition to my Lens collection.

I have both lenses for my Nikon D90. I have found the 35mm much more useful for indoor family shots. The 50mm is great for portraits and other jobs, but I just don't use it that much.

Set your 18-140 at 35mm and 50mm.
Take photos at both focal lengths and decide which best fits your particular application.

If you've only just started photography then you don't need either one at this time and may possibly never do so.

Your 18-140mm zoom lens covers both the 35mm and 50mm focal lengths. All you gain are wider apertures which help in low light and can give shallower depth of field if you've already learned how to use that feature. They also potentially give you better image sharpness especially towards the edges of the photos, but unless you already use a tripod or unless you regularly make large sized prints or have a really good digital projector then you won't see those benefits. You also lose that greater edge sharpness when those lenses are set at their faster aperture settings.

So the choice may be immaterial and is totally irrelevant unless you've identified what it is which either of those lenses has which you can't presently achieve with what you have. Buying extra lenses just for the sake of it, or for nostalgic bandwagon reasons (most of the 50mm primes!) is not only a waste of money but adds to the gear you need to lug around. Lens changing for the sake of it also has the potential to get dust on the camera sensor; even with camera which have automatic dust removal it's far better to prevent it to begin with.

But in short, if you have to choose then 50mm primes used to be the standard walkabout kit lens on 35mm film SLRs before zoom lenses became commonplace as their angle of view is very similar to what the human eye sees. They also maintain that angle of view on a full-frame sensor dSLR, but your camera has a smaller APS sized sensor so would have a narrower angle of view equivalent to a short telephoto lens of around 75mm in full frame terms. A 35mm prime on a full frame model used to be considered a slightly wide angle lens, and for many photographers the ability to capture a slightly wider view and then crop in slightly at the printing stage made them the standard default lens for press photographers as a quickly grabbed shot of a small group of people left enough wiggle room later on to straighten and crop the image. But on a modern smaller APS sensor dSLR a 35mm lens gives the approximate same angle of view as the human eye, so it now serves the same purpose for those cameras as a 50mm lens does for full frame models.

Personally I'd suggest that you buy neither lens. If you don't yet have one use the cash to buy a good quality tripod instead or save it to eventually upgrade from the kit version of the 18-140mm to one or two better quality zoom lenses covering the same focal length range when you start to notice what your current lens does not allow you to do.

For all-around shooting, 35mm. For closeup portraits (headshots), 50mm.