We switched our small community for watch collectors from Slack to Circle in March this year. The all-in-one package is definitely convincing. I haven't been as impressed with a tool as I am with Circle for a long time.
Unfortunately, there is one major point of criticism for me and my community: the chat feature is simply not at the same level as the rest. In contrast to modern messengers, Circle is unfortunately still lagging far behind. I hope they will improve this feature asap.