I like the Lebron one the best. The only bad thing is that the pic is blurry and I think you could have used better text but other than that it's good. The Howard one, on the other hand looks kinda plain, maybe you should make the logo more viewable?
Yeah I'm not feeling the D-12 text but otherwise I'm feelin that sig more than the LeBron one. The D-12 sig is pretty nice and if you could add some more text onto it and find a bigger picture than you can make this an excellent sig because it's too plain and the pic is too small and makes the sig look spaced out and plain.
The LeBron one is simple and effective but LeBron is a tad bit too blurry. The D-12 sig would be better with either different text or at least anti-aliased text...