Same, I only have one gan anyway. I probably shouldn't be voting as I honestly have no clue which is actually better, but I can say that GAN has the best premium cubes, but with a matching premium price tag (did I take that from a Cubehead video?)
It ultimately comes down to the user's preference. Personally, I like my Gan 11 more than my MoYu RS3M; but of course, the RS3M is a budget cube and isn't intended to compete directly with the more premium cubes. Although, the RS3M is the best budget cube imao.
I've had mixed experiences with the two brands. For one thing, Moyu is very budget friendly, but lacks in features and has some issues (for instance, even at one of the loosest settings the cube tightens up). GAN, on the other hand, isn't budget friendly, and can be a hit or miss brand for cubes.