I used Voat back in the day, from the beginning, when it was still called Whoaverse; to right around when it became a Nazi-filled shithole. But that doesn't really count too much since for a good portion of that time, it ran on a modified version of the old open-source reddit code. Whatever it moved to in the short time before the new ""community"" ruined was pretty decent; lemmy-ui reminds me of it a lot actually.

I used to be big into Imzy too, before it shutdown. Its software was somewhat like new Reddit, but like, actually performant and not a bug-riddled mess. I still miss it, but the lemmyverse, especially Beehaw, is filling that hole.

I've also used the old guard of forum software, I don't know what ran what because I didn't really pay attention to that kind of stuff as a kid.