I have the beta versions of Mlem, Memmy, Voyager, Thunder, and Avelon. My favorite has been Thunder so far because it has a unique UI and it doesn’t look like just a different variation of the same layout, like the others listed. I have a special exception for Avelon because it can load/embed videos and gifs within the app without opening the in-app browser, and it’s the only app among the ones I tested that can do that.