I'd probably want to go with Killer and maybe take out loaded. Also maybe deadly for the bosses and take out the bird health skill.
I have a nice pure gun build where it's the left and right trees with no bird. It seems to be doing a hurting on things so far and made the last areas a breeze but I have to experiment with bloodwing more to see how he works to truly say if this build is better than pure left and right. --- Xbox Gamer Tag-Rugal