If you really want a lens with normal focal length for Nikon D7100, the Nikon 35mm f1.8G is pretty much the best you can get.
However, I feel that the best lens you can get is the one you really want to use. There are considerations like focal length, aperture and things like that, but ultimately, the "best" lens in these categories will not be the best for you if you won't use it.
Generally when purchasing lenses I would recommend you to find out what kind of focal length you really like to use, i.e. start with the kit zoom and look at your images, filter them down to the ones you really like, in order to find out which focal length you most often want to shoot at. Don't get a "normal" lens because everyone says they're good and cheap. I have one; it's really good and really cheap, but I almost never use it, because I've never really been fond of the perspective i get from 50mm lenses. Focal length determines the general look of the photo in terms of the perspective.
Next thing you would look at is the aperture. Generally for "normal" primes, f1.8 is pretty standard. If you need a bit brighter, go for the f1.4.
Last thing you would consider is image quality, and price. There is no point buying a 70-200 f2.8 if all you want to do is shoot at 35mm. Again, I'm not saying getting a "normal" focal length lens is wrong, but do consider your own tastes and preferences before buying a lens blindly, solely based on the fact that it is cheap and good. Hope this helps.