Here would be my list, and the reason's why.
1. A fuscocaudatus (live in a world wildlife sanctuary in the middle of nowhere, can't be collected)
2. A. omanensis (Collection not permitted in Oman, but their range may extend into Yeman where they can be collected)
3. A. chagosensis (Maybe a hybrid between bicinctus and nigripes, too remote for collectors)
4. A. mccullochi (We don't see them in the U.S. but they do appear on occasion in Japan and Taiwan)
5. A. chrysogaster (live on a very remote group of islands, not much reason to collect there)
6. A. thiellei (hybrids are always rare and its not even certain where they come from, although somewhere around the Philippines seems likely)
7. A. rubrocinctus (you want to swim with killer crocs to collect a fish that looks like a tomato clown?)
8. A. latifasciatus (Although they are mainly from Madagascar, their range does extend to the African mainland. It would not surprize me if we get them on occasion, but they are misIDed as allardi, chrysopterus or clarki, even though the latter 2 species don't come from Africa)
9. A. latezonatus (Not common by any means, but there are quite a few that make it to the U.S. every year)
10. A. leucokranos (Not common in nature since they are a hybrid, but they come from an area that is heavily collected. If you have the right connections, you can get one)
There you go. The chances of you actually ever seeing one of the fish in the top 7 is very slim unless you go collect them yourself and apply for all the permits and such.