We've been to both LCBR and CBBR. If we didn't really care about the activities outside the resort and just went for the diving, would you go back to LCBR or go to Cobalt Coast for the first time? I like the idea of being able to shore dive but if the diving is that much better at LCBR we can go back there.
I have never stayed at CCGCR but I have visited and dived with their reef divers operation and it was a very nice place and good diving. And I have done a number of dive trips to GC over the years to shore and boat dive with different dive ops.
According to your profile you haven't done many dives yet (?) so you might want to give CCGCR a try and see how you like it and report back to the rest of us who are interested! The shore diving option will increase your opportunities for inexpensive dives and night dives.
Each of the Cayman Islands has their fans but I like all 3 of them! I think that LC does have the best diving because Bloody Bay and Jackson's Bight are fabulous but keep in mind that if the weather turns against you and you have to dive the south side then the diving is nice but nothing too special.
Brac diving is very good IMO and you have more options to find good diving on different sides of the island if the weather isn't cooperating. Plus the Tibbett's is a fun wreck dive and there is more natural beauty to enjoy topside on Brac than on LC. I think that it is the most dramatic and topographically interesting of the 3 Cayman Islands.
Grand Cayman has a lot to offer. The Seven Mile Beach is spectacular. There are wonderful restaurants, shopping and topside activities. There are both developed and undeveloped parts of the island so you can pick the area that you like best.
You also have a lot of choices for very good diving around different sides of GC if the weather is an issue. I think that the East End has some of the best diving IMO but it can get rough. There is very good diving off the North Wall but it isn't always available in the winter months. I've also had some nice dives off the south side when that area had the best conditions. The corals on the West side are not always as dramatic as the East and North Walls, but there's lots of fish life and some interesting wrecks including the Kittiwake, and the weather is more likely to be calm on the west side when things are too windy and rough elsewhere.
Since you have already dived Brac and Little you might want to give Grand Cayman a chance. Cobalt Coast is in a more remote area of West Bay, north of 7MB, but not terribly far from things. And everybody should dive Sting Ray City at least once. You might consider renting a car for a couple of days and exploring.
I should mention the one thing that GC diving doesn't offer that you get in the Sister Islands are all the friendly groupers. I love those groupers and there are not many around GC, but you will see lots of tarpons, turtles, eels, colorful tropical fish - loads of rays - masses of silversides during the season, and some sharks so it should be a good time.
If you do decide to go to CCGCR, I suggest late Spring or Summer because that is the time of year when you are most likely to be able to shore dive the house reef and dive the nearby North Wall. The house reef can get winded out during the late fall, winter, and early spring.
You already know that you like the Cayman Islands and that Clearly Cayman and Reef Divers run a nice operation together - so why not give CCGCR a try?
But if you want to take greater advantage of the topside attractions of GC, then there are other places to stay and dive ops to consider as well as CCGCR.
Let us know what you decide!