If it's a duel you're wanting I feel bad for you Son Draigo killed 99 great demons But M'kar ain't one.
Well for me it's Nurgle obviously, I almost never got sick and I'm pretty resistant to pain, but even more, I really love all kinds of deceases, parasites, virus, fungis, symbiotes, nuclear, chemicals things and evolution-based lifeforms (Zerg/Aliens/Tyranids and co) I might work in an Hospital in the near future too soooooo .. Oh, and I have a little Gas-mask fetish x) In second place, Slaanesh for Art, Music, Sex and Drugs with Tzeench for my curiosity and the fact that I read alot of books.
Yes I did over seas in Afghanistan and had R&R in Amsterdam. now what I did I can't discuss here but lets just say I made all 4 gods very proud.