Wolf one is the best, without any doubt.
The first one has potential if you used better FX.

Second one has nice lighting, but you could've brought the yellow from his bottom body out a bit more and the blending needs major work.
Third one has a decent concept, just needs better lighting, contrast and FX.

Fifth one has poor lighting and the way I can see the blurred BG like that makes it looks really unappealing.