1st;
I don't really like this one. Too much purple IMO, and get rid of the splatter is his face. It looks kinda weird. Also, make the left side of the sig more.....how do ya call that? erhm, well just make more going on on the left side, it's kinda plain.... Lighting and depth could use some work too...
2nd;
Nice work on this one,I like it

Nice bg and render, and the lines are pretty cool

However, the lighting could use some work....