Butterflyfishes, Tangs, and Angels are my favs. They actually do go together well because most fishes in each group tend to eat slowly and pick at their food. When you get a Butterflyfish that eats voraciously, that's a keeper!
The Butterflyfishes will do best in communities that are not fast or pushy eaters. Keep them with other lay-back fishes. BUT, have at least one or two other fish in the tank (dither fish) that will come forward and show them they don't have to be afraid at eating time.
They get along pretty well with each other, even those some are competitors. One or two may attempt at the king of the hill position, but you just have to watch out for it. Give them as much space as you can. I like a 125 or 180 as a minimum.
You have begun in the right direction, Ed. You're looking at what they eat. Absolutely don't get any Butterflyfish (or any other) that eats just coral. Coral obligate fishes are just not for the hobby. On the extreme other end of the spectrum, those that are pod eaters can be accommodated easily -- not easy to keep necessarily, just easy to accommodate.
On the list of fishes in this group easy to keep you'll find the Raccoon, Heniochus, Yellow Longnose, Vagabond, Orange, and Auriga. Not all of these individuals will work out well, but most do. In the medium class are some fine fishes: Tear Drop, Copperband, Latticed, Dot-Dash, etc. Avoid those that are usually more difficult if you want an easier time of it. Like don't invite a Saddleback, or Mertensii into the group. These fish are a hit-or-miss, with most of them dying off in the first year of captivity. I would avoid the Tinkers unless you know for a fact at what depth it was collected. It's expensive, but if collected deep, not worth trying to 'trap' in an aquarium. One collected in shallow reef waters is good. They are in the easy to medium class. This goes for many of these fishes. Those collected deep usually don't do well in captivity.
Make sure you quarantine them first and train them to eat properly. Offer the best foods! Put in with proper tank mates. Keep water quality high AND steady, and all should be fine. It's important to see the fish eating before you acquire it.
Hopes this helps some.
