I’ve been looking for the right Wiki for a company that consulted me. After looking around for a while, I think I’ll try [ PmWiki ] – users can upload files to its pages and it’s still relatively easy to setup.
Anyway, if you’re looking for similar information, here are some links to begin:

[ first comparison ]
[ second comparison ]
[ third comparison ] (most comprehensive)

note:
it looks like that [ DokuWiki ] is quite good too.