The absolute, very very best, imo. For style and effectiveness on a sneaky toon.

Sword mainhand, dagger offhand. Why this? Well, a few reasons: One, the sword animations are just cooler than those of the axe or mace. Two, the dagger offhand makes your swing speeds for the double attack really quick, and the sword gives you reach, which is very, very helpful in stand-up fights. You still get the wicked throat-slitting animation on your sneak attacks, which is an important style win, and for really tough enemies you don't think you can one shot with the sword a double sneak attack will drop them quite nicely.