I have used both in test plays. I was not very extensive.

SkySA has more third-party movesets available, and a guide for creating them, as well as the author's previous animation guides to facilitate their release. It is very rigid. I was annoyed because many weapons swung slower in first person than in third person. It's also probably not possible to complete Bloodskaal Barrow with it installed, since BSB requires sideways power attacks, but I didn't get this far. However, the animations are top quality if a bit high fantasy, and unlocked grip was just released for it. Note that it has to be installed correctly or you'll lock up in combat. I found myself dying a lot, but it was a consistent experience.

CGO + ABR fixes some of the compatibility issues of CGO (it lets Animated Armory work with it more seamlessly), and nothing has made me feel more like my D&D character. However, there are some bugs, notably you have to delete a certain file or else shield-bashing will put you in an infinite run and disable your weapons. Also, first-person jump events do not work if you have any mods that use them, and again I had some trouble with different swing speed between first and third person, but I believe it was fixed by turning off modifiers for grip switching. The CGO weapon animations feel a lot more balanced and realistic, and weapons in a 2h grip are rested on the shoulder when not in use which is nice. I died a lot to mages in particular, but had a load of fun fighting, as long as I didn't run into any bugs that locked me up. Unfortunately the enemies were also affected by the blocking bug.

Adri's patreon following seems anecdotally more eager to advertise to others.