Those add-on ringflash things for your speedlight are big, clunky and easily broken, to say nothing about the loss of light while it is bouncing around inside the unit.
For the same or less money, you can buy a proper ringflash from many of the Chinese websites and the one I got really works well. It might be fully manual, but you can easily adjust it from the camera menu, and for around $130 - it's fantastic.
Works well for portraits and gives a very nice circular spark in the subject's eyes.
If you want slightly different lighting from one side to the other, you can just drape bits of tissue over one side of it.
That way, it gives nice slight shadowing to one side of the face.