Edit: lemmynsfw.com has been uncensored instance wide so anyone may view it’s contents without requiring an account! Might remove or at least un-pin this post later. Thank you to everyone who has participated in this thread so far.

The top ones currently (in no particular order):

• !porn@lemmynsfw.com - All things porn
• !porninfifteenseconds@lemmynsfw.com - The unofficial successor to /r/porninfifteenseconds!
• !hentai@lemmynsfw.com - General Hentai Community (and successor to r/Hentai)
• !gentlefemdom@lemmynsfw.com - For gentle female domination.
• !aigen@lemmynsfw.com - For AI Generated Porn
• !tentai@lemmynsfw.com - Tentacle Hentai
• !futanari@lemmynsfw.com - Futanari Hentai
• !nsfwworldbuilding@lemmynsfw.com - Not Safe For WorldBuilding
• !rule34@lemmynsfw.com - Rule34 content