Ask HN: Where to host a betatester/users community?

So we're releasing a fintech-related app to betatesters and early users, and I'm looking for a place to host a small community. Posting updates, taking polls, asking questions. Connecting with users. Our product is strong on integrity and privacy so I'd prefer not to use Facebook even though a facebook group is almost ideal.

So where? We need something hosted, easy enough to use for users that aren't very technical, and that doesn't require a complicated user registration process.

I'm interested in the latest but would prefer the greatest :)

All ears.