both sigs arent very good meh but howler's one was better. not gonna comment on ninjaman's sig but imma cc a bit on howler's.
first thing is you darkened the focal (which is obviously, the render, which is naruto) and brightened the bg. this makes people distracted from the focal and look at the bg instead, which isnt good
well secondly, it looks like u didnt plan how you smudged the naruto. it just looks like you smudged in random directions. that doesnt make the sig look good and makes it look messy. next time smudge with flow or sth. ( for example, follow the direction of the render. look at naruto, he is facing the left side. it would be nice if you could smudge to the right side, following the flow)
thirdly, there's a piece of black there on the lower left corner which looks outta place and random lool