I would recommend MyBB. phpBB is a good software but MyBB is somewhat better. MyBB is basically a forum software for those newbies. phpBB offers great modifications and themes, but there's just one major problem. Installing modifications required file editing. I know the modification folder offers a installation guide, but sometimes the person could get accidentally mess up and could get an error. Do you have to do all that again? unless you backup your files and databases. As for MyBB, all you need to do is just upload the files to the correct directory and activate the plugin. It's that simple. But I have to agree that phpBB styles are better than MyBB themes.