As some of you are aware I recently got a Sony a 6000. Now it came with a 16-50mm Power Zoom Lens and I have been able to take some pretty decent pictures with what I have such as:
or (This one I did enhance with Lightroom):

Anyway I got a bonus from work and I thought, hey I could get a lenses with this bonus and save the rest of the bonus. So I need your help in choosing just one lens. I narrowed it down to three. They are:
Sigma 19mm f2.8 DN Lens (Sony E) - Fixed ($199):
Sigma 350965 60mm F2.8 DN Lens (Black) (Sony NEX) ($209):
Sony SEL50F18/B 50mm f/1.8 Lens for Sony E Mount Nex Cameras (Black) - Fixed ($248.00):
Which of these three lens do you think I should get and why? If it helps I want to do closeups of small objects like a flower or watch. I can do buildings but I want to also do stuff that is smaller than a building.