So which saga is most fanfic-able?
My vote is for Laxdaela Saga. Take two foster brothers, Kjartan and Bolli, who are cousins, totally cousins, and add one woman, Gudrun, who loves Kjartan. Send Kjartan off to Norway without her to make his fortune, leaving Bolli the chance to tell Gudrun about the little royal bit Kjartan's getting on the side, and so marry her instead. Blend in some goading by Gudrun and simmer until Bolli finally kills Kjartan, who dies in his arms in a completely cousins, totally cousins, sort of way. And that's just one central episode -- there's beards spread across broad fjords and pointed questions by grandsons about old romances. Not to mention the name of Kjartan's father, Olaf the Peacock. Lots of tasty material to work with here.
But arguments for others can be made. So make 'em -- what's your pick?