First flash: MeiKe or Yongnuo?

I'm a high school student and photography is my hobby. I just recently got a Nikon D7000 and I am looking into a flash. There's no way I can afford a Nikon-brand flash, and I had read some good things about the MeiKe Speedlight MK900 and Yongnuo YN-568EX. Anyone have any insight on which one is best? I would probably be using it mostly for portrait shots, but experimenting with it, too.

Again, photography is a hobby, not my profession. I am just looking for something to get my foot in the door of flash photography.

Thank you so much for any insight and help!