Allefant
Am I supposed to have a "homepage" here?
Well, not much to say in any case. I like Moin a lot, I'm using 3 other wiki engines currently as well (all for open source stuff), and Moin clearly wins.
TWiki is a mess and a horror to maintain compared to it (but I'm admin at one and can't convince them to switch). WikiSever just is not up to current wiki standards from what I see. And of course MediaWiki, which is very nice. I especially miss the section editing like there on Moin. I was made admin at a fairly busy mediawiki, then managed to destroy all pages with a small coding mistake in my (python) bot - which was very embarassing, but then I could easily restore them all again, only leaving 1000ds of message in RecentChanges of my mistake. Anyway, that it was so easy to simply treat my bot as vandalist and revert all its changes made my regard for mediawiki go up 
Moin I'm using as documentation system locally, and for my site about my hobby retro games at SourceForge: http://allefant.sf.net.