As a man, I dislike the butterfly one simply because its a butterfly and Bart Simpson is cooler.
Now getting to a level where graphic criticism comes in:
#1- The flow is good, the render looks like he's flying, having a light source is something I always like to see. Having monotone color sigs can sometimes be good because in this case everything color wise blends.
#2- Very similar style as the first one but I think the right side is a little too bright and it does'nt reveal lighting as well as the first one. The blues from the butterfly itself and the background don't blend as well as the first one.
Relating back to the first sentence I typed: Render choice is always an important factor because it can attract a different audience, Example: Mariah likes the butterfly, AtomicFlame likes Bart Simpson. We may not have very many females on this site so put that into consideration for your next SOTW Entry of how guys like manly things in sigs.
I'm done, no more rants from AtomicFlame today be at peace.