phpBB has a simple, user-friendly interface, a helpful FAQ and a generous administrator control panel.
You can choose the databases server (MySQL, MS-SQL, PostgreSQL or Access/ODBC), the functionalities (at first I was a little discouraged by the mods installation process but I found great support on the online community and the documentation they provide answered all my questions) the skins... Everything is customizable so you can create the forum you wish.

If you haven't got much time, and want to see what the new phpbb3 can offer, just try it out on this host : free forum hosting

Hope this can help!