Almost anyone could get the job done, but who could you trust to not turn around and try and whack you.

I think I have to go with Murder Inc. That's because those killers were not chauffeurs or bodyguards or what have you. They were like an outsourced hit team that didn't even know who the orders were coming down from. Not safe to use them either, but probably safer than all the rest.

Any other type of hitman has to be rewarded with a promotion for the hit, which in turn makes him more powerful, and more dangerous to yourself.