This one.
Any others?
Sure, lots. See http://sunir.org/apps/meta.pl?delet. A summary:
- FatWiki
- FoxForumWiki
- MoinMoin
- OpenWiki
- PwpWiki
- TwikiClone, page deletion can be restricted to any group
- UseModWiki recently added administration deletion, soon to have peer reviewed deletion.
- WikkiTikkiTavi
- WikiNi
- WikiWiki, but not WikiBase
- ZwikiWeb
- WackoWiki
See also: WikiWikiClone
The above refers to wikis which have explicit delete functionality rather than those which let you delete things by shutting the system down or manually deleting the page from the file system or database table.