They are both very good.

1. Colors are nice and BG is nice but the render is soo tiny tiny. I kind of wish he could have been bigger cause it would stand out a lot better. Compared to the text too he's a midget lol. Maybe make the text a tad smaller and crop in to make him seem bigger? besides that great job.

2. this ones my fave :P. I think you should blur the BG a bit though to give it some more depth and to bring the focal out more. besides that great job, nothing else to critic on that sig everything good.