They want an online forum/community. Would you suggest using the built-in Journal/Social Groups for an online forum/community? Or is there something different/better out there? I've never used this before so unsure of how well it all works. Just looking for a place for all the users to chat and share info.

1 - In terms of Forum you could get the Active Forums - http://activeforums.org/

2 - In addition, you can check the DNNHero video series on how to put groups and journal together to build a social site: https://www.dnnhero.com/Videos/DotNetNuke-Social