Your favourite community apps

What are your favourite community / group apps? And what do you wish they had? I'm doing some research into this area and would be curious to hear everyone's thoughts. To provide some context, we started a conversation app called Multytude, and it's starting to turn into a place where communities discuss and make decisions together. Before we go down this route, I want to explore what users of other dedicated community apps look for. Don't want to pivot unless I see we can offer a differentiated solution in this space. Thanks all! 👊