Both are pretty solid. At the moment magdk synergies really well with the dots. Stamdk is just as good with dizzy swing. It's more preference. Do you like stamina or magicka? Go nord for either imo. Sustaining is super easy on magdk.
When playing nord magdk I used blood spawn/crafty alfiq/spinners front bar. Death wind SnB back bar. Really strong and tanky.
When playing nord stamdk I used blood spawn/medium clever alchy/all infused weapon damage jewerly hundings. Spriggans would be better. Hits very very hard.
So I wanted to make a DK and mostly do no-cp PvP. I was wondering which spec you guys think is better for that, Mag or Stam?