How about one of the merchants in Raven Rock's square? The smith,the Alchemist lady.....maybe the one that buys the East Empire pendants,all are unessential npc I believe.
The three ones you could kill that are on the high-profile list are: Fethis Alor the Pendant Guy, Garyn Ienth the unimportant farmer, and Milore Ienth the Alchemist. I'd go for Garyn