I don’t know why these sites are so popular, or were until recently, but I’ll post links to them out of service to the populace. (Or, alternately) as bookmarks for my own eventual perusal. These are addictive and grotesque at the same time – much like playing Doom.
Sorry:
www.whatsbetter.com
www.celebritybattles.com
and, also,
www.hotornot.com
With the special German wersion:
hotornot.whow.de