Keeping in mind that I'm stupid and I'm not willing to make that much effort to test stuff in a short period of time, here are some yes/no judgments on wikis for my purposes:
Bitweaver - I can't make this go.
Daisy - Too much command-line crap to deal with to install.
DokuWiki - No, CamelCase is not user friendly.
Drupal - Nice looking, respected, but baffling to me. Not really a wiki.
Foswiki - No, CamelCase is not user friendly.
JSPWiki - No, CamelCase is not user friendly.
MediaWiki - No, no good WYSIWYG.
MindTouch - No, commercial.
MojoMojo - No, no good WYSIWYG.
MoniWiki - No, CamelCase is not user friendly.
Oddmuse - Not full-featured.
PhpWiki - Can't make it go, little meaningful online support.
PmWiki - No, no good WYSIWYG.
ScrewTurn Wiki - Still getting to this.
Tiki Wiki CMS Groupware - I like this.
TWiki - No, commercial.
WackoWiki - No, no good WYSIWYG.
XWiki - I like this.
Naturally there are ways in which I am wrong on some of these: there are ways to have links without CamelCase where I say there are not, and there are ways to get WYSIWYG editing and so on. But I'm a dummy and dummies want what they want NOW NOW NOW and don't wanna spend time fucking around with configuration and plugins and permissions and so on. Maybe some touchy developers will come by and explain things after they tell me what an asshole I am.
As an out-of-the-box instant wiki to test XWiki comes with a nice installer for Windows - Mac zombies left out - and you just have to remember to point your browser at http://localhost:8080/xwiki/ after it's done because it assumes you're smart enough to know that.
Apart from the standard wiki one of the things I need to help do is put together at least two documents of a similar form with similar tables of contents: XWiki sets up namespaces pretty quickly so you can have two different areas accessible from your home page that are populated with wiki pages of the same goddamned name without conflicts; that is, a page called "History" in one namespace doesn't encroach upon a page called "History" in another namespace. Quick and easy, the way it should be, although further testing may reveal that it's too easy to leave a trail of orphaned pages everywhere.
Tiki seems way more powerful than XWiki in a bunch of respects, but I haven't figured out how to keep a "History" page in one section separate from a "History" page in another - look at this baffling bullshit about "workspaces" and let me know if it makes sense - although a cheap and dirty solution is just to set up another MySQL database and start up another Tiki folder on the same server, but that seems dumb. There's probably just something I'm missing, but hello, more documentation for the morons please. My hope is that I figure out a solution in Tiki because administration seems easier than in XWiki and it does more stuff, but the instant and obvious utility presented to the user of an XWiki site is powerful stuff.