I've clicked a little through wikimatrix, and let it show me all wikis with GUI editing:
http://www.wikimatrix.org/compare/%40Wiki%2Bbitweaver%2BBrainKeeper%2BBusinessWiki%2BButorWiki%2BCentralDesktop%2BClearspace%2BClearWiki%2BcodeBeamer%2BConfluence%2BCorendal-Wiki%2BCospire%2BDaisy%2BDokuWiki%2BEditMe%2BFoswiki%2BGeniusWiki%2BGiki%2BGroupswiki%2BIkeWiki%2BIncentive%2BIntodit%2BJSPWiki%2BKeheiWiki%2BLuminotes%2BMediaWiki%2BMetadot-Wiki%2BMidgard-Wiki%2BMindTouch%2BMoinMoin%2BMojoMojo%2BMoniWiki%2BNetcipia%2Bnexdo%2BOddmuse%2BPAUX%2BPBwiki%2BPhpWiki%2BPmWiki%2BProjectForum%2BPukiWiki%2BSamePage%2BScrewTurn-Wiki%2BSharePoint-Wiki-Plus%2BSocialtext%2BSpringnote%2BSwirrl%2Btelepark.wiki%2BThoughtFarmer%2BTiddlyWiki%2BTikiWiki-CMS-Groupware%2BTraction-TeamPage%2BTriki-Wiki%2BTWiki%2BWackoWiki%2BWagn%2BWetpaint%2BWikiDoc%2BWikispaces%2BWikkaWiki%2BXoWiki%2BXWiki%2BZoho-Wiki%2BZwiki
They have 123 wikis in total, the query returns 64 Results.
Those with No syntax at all (like our group edit):
BrainKeeper, Groupswiki, Incentive, Intodit, Luminotes, Metadot Wiki, MindTouch, Swirrl, telepark.wiki, Wagn, Wetpaint, XoWiki, Zoho Wiki
Those with Some syntax:
IkeWiki, nexdo, PAUX
See the matrix:
http://www.wikimatrix.org/compare.php?prods[]=87&prods[]=103&prods[]=28&prods[]=92&prods[]=127&prods[]=110&prods[]=102&prods[]=80&prods[]=53&prods[]=85&prods[]=132&prods[]=90&prods[]=133&prods[]=65&prods[]=68&prods[]=124&x=52&y=10
Notably most of them are proprietary or only available as hosted solution.
There also is: http://www.wikicreole.org/ which aims to provide a syntax subset each wiki should support to ease users to switch between wikis. naturely its not supported by these gui wikis.
