I'm really enjoying my flame-themed mag DK in PVE. It still needs a lot of tweaking to be optimized, but I parsed him at almost 70k with a terrible rotation, very little practice, and less than optimized champion/gear setup so I know he can be really strong.
I'd say Stam. Because PvE heavily favors Stam. Stack in Weapon Damage and enjoy the ever rising damage.
For PvE it is probably best if you take Flurry as a spammable and a Maelstrom 2H backbar.
The class spammables are not so great for StamDK.
If anyone here says: OH! But, PVP! I swear I'll ...
Thank you for the valuable input and respectfully recommend to discuss that aspect of ESO on the PVP forum.