I've been on Minds and Gab since they started. Minds is quite good, but its more of an image board suited toward non-text based posts. This does mean that peoples text posts stand out though, amongst the flood of image memes. Its also good for news from around the world.

Gab.ai I barely ever use. I joined it because people on YouTube were recommending it, especially after it as found that the other promoted social media platform (which I have forgotten) was found to harvest your data. Im not sure why gab exists. I havent used it since the moved to the .com domain

edit: Hrm. I just checked my gab account and it appears that all of the posts (all 18 of them) I have replied to have been removed.