i have also been told that the diving around anguilla can be pretty awesome. however as far as i can tell there is now only one dive shop there. i could be mistaken though. some people i know chartered a dive boat there and they said it was amazing. anguilla is another island like statia mentioned previously, that does not get alot of attention. but i think anguilla prefers it that way. they want to remain an exclusive destination.
I have been travelling annually to Anguilla (AXA) for the past 8 years. Discovered it during a day trip from SXM. We love the Island - wonderful beaches, quiet, great restaurants, friendly. While on the Island I always go diving. During a 3 week stay I get in about 16-20 dives. There are currently 2 dive operators on the Island - Scuba Shack and Vigilant Divers. I believe there is another operator/individual who will take out divers but have never been able to contact them. Except for the first year I have dived with Scuba Shack (formerly known as Shoal Bay Scuba). The first year I dived with Anguillian Divers but they went out of business (I could see why). I have heard very positive feedback about Vigilant Divers and have had no reason to switch as Scuba Shack has been very good for me. Both dive ops are small when compared to operators in well known dive destinations in the Caribbean. Boats are safe and clean. With Scuba Shack max capacity on a boat is 10 and this year was the first time I experienced 10 divers - note, that I go late April/May which is the start of of the low season. Cold water and a snack is provided during SI. Backwards roll in and equipment off before getting on board as the exit ladder is smallish.
In terms of diving, there are about 6-7 wrecks and about 16+ dive sites not including the dive sites on sister Islands - Dog and Scrub. Other than Dog and Scrub all the dive sites are all within a 5-20 min boat ride away. There are no walls per se - except at Dog (it is about 13 miles away and will only go there if seas are calm which is in the summer so I have never been there). In April/May the viz is on average approximately 60 feet. Looking at log books this is consistent over the years. I have spoken with other divers and viz is much better in June/July. Viz always improves towards the end of our stay. Water temp in April/May is about 80-82.
Many of the reefs are filled with soft corals. Other than the wrecks there is no mooring line for the boat so down goes the anchor...and too often hitting the reef. There is not an abundance of fish (IMHO it is over fished and there isn't a marine park established to protect the reefs) however there is a decent variety of marine life. As I have become more experienced over the years I tend to take my time now during dives and hence I see a lot more. I am currently on Island and during 2 dives I spotted 7 varieties of Hamlets. Most years we see turtles, sharks (nurse and reef), octopus, tarpon, eagle rays...and always Southern Rays. The other day a dolphin was spotted. Not seen a green moray but plenty of spotted, golden tail and garden eels. Truck fish, cow fish, porcupine, burr...the list goes on. During a night dive this week I saw one of the largest Southern Rays I have ever seen. Plenty of different invertebrates.
I am not a fan of wrecks so can't comment about the wrecks themselves but there is always plenty of marine life to see and several are close to a reef so can quickly take a diversion from the wreck.
I always manage to come away from our stay with plenty of pictures and each year manage to see something that I have not seen before - either in Anguilla or elsewhere. When looking at marine life reference books I take note of the many pictures taken while diving in Anguilla. I like the fact that when diving you don't bump into other groups of divers and their are no boats zooming on the surface - making it a very peaceful dive.
A link to some photos from the first week of our April/May 2017 stay in Anguilla.
https://drive.google.com/open?id=0B0moWNZKb4jCLTNBV3lLNDNRUmc