BBCode vs. wiki markup for collaboration software

I'm developing a web application to facilitate the playing of pen-and-paper RPG开发者_StackOverflow社区s over the internet. I'm trying to determine whether BBCode or some flavor of wiki markup is preferable. BBCode and tikiwiki markup both have packages in the PHP::PEAR repository and I admit a preference for tikiwiki, but I haven't been able to figure out much in the way of qualitative differences between options.

Do you need markup? Is there some reason a WYSIWYG editor wouldn't do the job? See eg. the FCKEditor extension for MediaWiki:

http://www.mediawiki.org/wiki/Extension:FCKeditor_(Official)