Which camera prime lens I should buy for my Nikon d3200? And why?

I'm looking for buying a new prime lens for my DSLR Nikon D3200. Please tell me which lens I should go for and why? (50mm or 35mm) And tell me if I'll be able to use them for long time purpose(for my next nikon dslr) or not?

Unless you really need a prime lens, then pick one of the zoom lenses that will add to your 18-55 mm lens.

To see if the 35 mm or 50 mm is more to your liking, spend a week with the lens set to 35 mm and shoot everything with that setting. The following week, tape the lens at 50 mm and do the same thing.

By the end of that time, you will have a better idea of what focal length lens will suit you the best.

ANY of the Nikkor AF-S or AF-P lenses can be used on your D3200 up to and including the Nikon D5. Why? Because the DX lenses automatically crop a full frame sensor to the DX size.

While you may be thinking that you need a prime lens, you have to ask yourself what exactly you expect a prime lens to do that a zoom lens (withing the same focal range) can't.

One prime lens you may want to consider is the Nikkor 40 mm f/2.8 macro lens. It is almost as wide as the 35 mm, however it can take extreme close ups of your favorite subjects

Here is a link that discusses closeup photography which you may find fascinating