Tildes is mentioned often as it seems to be the most visually like Reddit on first inspection. But it really isn't.

Their philosophy is totally different than Reddit. They want text posts only with only serious, long form discussion. No lighter topics like memes, which make up a humongous portion of content on Reddit.

It's invite only. You can't just easily sign up for it. Most people aren't going to try to find someone to ask for an invite when they can just click back to Reddit.

Unfortunately the RIF is Fun dev has picked Tildes to go to, which makes for even more people talking about it. But Tildes doesn't want to be a Reddit replacement at all. It wants to be a small, insular community with only serious, long form discussion.