Genicanthus angels will be the most widely accepted as "reef safe" angels. However, many angels live quite successfully in reefs. Depending on the reef type and it's inhabitants you can minimize risk. Angels enjoy clams, there is no getting around that. That's not to say any and every angel will pick at clams. However, clams are generally one of their favorite things to pick at. Sponges being their first. LPS and other soft coral types are also more at risk than say SPS corals. Again, nothing is constant and an angel may disregard softies and pick at SPS. The key is knowing your risks, minimizing them, and weighing the pros and cons. I would profoundly disagree with aquaman06 in stating that you must make a choice between your tanks focus being fish or coral when introducing angelfish into an aquarium.
Not a fan of butterflys, but many of them are obligate coralavores. The copperband NOT being one of them. Generally forcipiger butterflys are the safer variety in a reef. Some chaetodons as well. Again, this isn't set in stone. Any fish can pose a threat in a reef system. It just depends on what you define as a threat, coral eating, bullying other fish etc.
