Wowzers. Tough call. Two totally different takes on the subject matter. Both has some anatomical issues. Though the problems may be less obvious in Spidey's piece.
Armstrongs has a lot of energy and movement. It feels pretty epic. Though Darkness seems to play second fiddle. I think the use of shading and spot blacks kick up the contrast on the piece, though I could use some more line weight on Witch, since she is up front, especially around her right hand, which gets lost a little.
Spidey's has lots of personality. I don't read the darkness but I've always liked the idea of his darkness imps and their personalities and I think they are really shown off. The one peaking over the Darkness' shoulder, the two arguing, grabbing his junk. But what really got me was the one touching Witch's booty. I think if Witch reacted to that a bit, it would have been awesome. Also really dig the line work on this piece but it is screaming for color.
Went with Spidey for style reasons, anatomy, and imps.