Even if it is better, it seems he is on a tight budget. Using PhpBB he will have several free skin options. But I think PhpBB is the best free software. There is also invisionfree. The free IPB board.
Your message seems to imply that SMF isn't free, but I don't think you intended that. A quick search showed up plenty of free SMF skins, and I've read a few messages in the past saying that SMF is more secure than PhpBB. Try searching through the threads here, there'll be plenty comparing forum software, e.g. http://forums.digitalpoint.com/showthread.php?t=433428
Depends on which platform you want..DOTNETNUKE is a very good option if you are planning on windows platform..
You can find Ratings of all Forums on the OpensourceCMS web-site. Click on "Featured Articles" and then "CMS Ratings". You can also try demo of all forums on this site.
I would recommend SMF its lighter - uses less server resources , more secure - if you run phpbb you need to pactch it each and every week or it will be exploited. Free Php Forum Scripts