Necrolord was my pick, though mostly for thematic reasons. My rogue is undead, Maldraxxus was my favorite zone, and the Necrolords were my favorite covenant. Honestly none of the rogue abilities were all that appealing to me, with Night Fae probably being the best, but no way was I going to be Night Fae or Kyrian. Venthyr is cool enough that I would play them, but Fleshcraft is far more useful to me than Door of Shadows.