I want to hate this, but I am sadly disturbed that you are correct. But a lot of people don't know anything about either organization. I try to educate when/where I can.
@OP I just donate directly to specific shelters. With my time too, when I can. I happen to be a no kill proponent and a feral cat colony caretaker. So HSUS at least pushes that agenda some, IMO, but after I entered the reptile world they are just as dead to me as PETA's crazy BS. Pick an organization or shelter to support.