Cristian, I merged your two threads since they basically are the same question. There is no point in posting the same question in different forums. I hope you understand.
Now I can try to answer your question. The choice of a lens is a very personal choice. Some people like to use fixed focal lenses (35mm 1.8 DX, 50mm 1.8) While these lenses don't offer the same convenience as a zoom lens, they will give you the ability to take pictures in less light and will have better IQ (Image Quality) than most zooms.
So, since I don't know what your expectations are, nor what kind of pictures you would like to take, but I would recommend the 35mm 1.8 DX lens. It's one of Nikon's less expensive lens but offers superb IQ for the price. It can be used as an "all around" lens without worry.
All the best.