Best lens? Nikon 50mm, nikon 35mm or sigma 24-70mm?

I don't know which lens to use for nikon d3100
Interested in people street, urban, interior photography
My camera is crop factor
And i'm lookin for wide aperture lens
If you would answer please give some details

A 24 to 70 is 'wasted' on a crop-frame camera such as the D3100, that lens is intended for much more expensive 'full-frame' cameras. For the equivalent on your D3100 get a f2.8 17 to 50mm.

Which version of each lens? How much do you wan to spend? What else do you have?

In general, the 50mm f/1.8 is an awesome lens, but you are locked into a single field of view. It is great for head and shoulder portrait shots with your camera due to the crop factor. This is the best bang for the buck lens out there.

The 35mm is going to be medium wide on your camera. Assuming it is the f/2.8, then it is a nice lens to have if you like primes.

For versatility, I would get the 24-70, assuming it is a constant f/2.8. I really like the lens for walking around and general photography. It is not very wide, so you may have to make panoramas by stitching shots together if you want something really wide, but it has a nice range. An alternative is the 16-35mm (or something close).