BuddyPress.org

Agree with Andrea_r. Note that the oneclick install forum doesn’t have as much community support as far as plugins go as the standalone bbpress does.

At the end for forums I think nobody beats phpbb. So whatever your focus is as a site/communicty/group go with the best extensible available solution. If forums is your core look at forum software that gives you what you need. I would hold back for investing in a swissarmyknife, but fail at the one thing that is important for your audience.