Everything. I want everything in my city and I want it to takes ages to build
Website - Websites are awesome, especially when you have a pretty solid group of active players.
Maps - Maps would be awesome, I love seeing settlements on other planets when i look up at the sky, having a map (or even the https://www.boundless-maps.com - not working atm) would be awesome.
Streaming - I stream on YouTube and really love it, building a community how ever small it is around your stream is real nice and a great way to meet nice people in game. I also love watching other people stream, especially when they do different things than you, ie: Hunting, Centraforging, Shop Keeping etc.
Videos - Same points as streaming, love making them and watching them - its how I learn, not a fan of written guides, by videos I get it first time.
Discord - Love using it when on hunts or group builds, especially when playing with ps4 players as it takes them alot longer usually to type. Plus getting tours of players builds/bases on discord is great. Again, awesome for building bonds with people.
Guilds - great idea, brings people together and encourages people to play for a joint cause, like a guild build/farm/portal system - plus the awesome buffs that I haven’t even tried out yet