Nikon d3100 18-55mm or 18-105mm lens?

I take wildlife, nature, macro, and street photography.

The 18-55mm is an excellent lens when you're just getting started and is superb for street photography. The extra pulling power of the 18-105 isn't enough to justify the extra expense.

The 18-105 mm is not long enough to shoot wildlife (300 mm would be the minimum focal length for that - Look at the 55-300 or 70-300 mm lens for those shots)

Neither of those lenses are macro lenses (look at the 60 mm or 105 mm f/2.8 macro lenses)

The 18-55 mm is fine for shooting street photography

The 18-105mm lens is optically a better lens. Whether or not it is worth the extra is debatable.

Here is a simple test on the 18-105.

http://www.althephoto.com/lenses/kitlens.php

And the similar test on the 18-55. Notice that at 24mm and 35mm the lens is a bit soft in the corners:

http://www.althephoto.com/lenses/super-zooms.php