Daggers have the fastest attack speed of any one-handed melee weapon. Maces have the slowest attack speed of any one-handed melee weapon. Your off hand weapon dictates your dual wield attack speed. If you put a dagger in your left hand your attack speed will be measurably greater than if you put a mace in it.
I generally recommend using the dagger in your off hand for your starter build because the damage difference between a mace and a dagger is negligible and you may actually net a benefit in damage over time with the dagger, especially because the number of power attacks you can deliver at lower levels is limited by your relatively low stamina.
When your One-Handed skill increases enough, you'll probably want to abandon the dagger because the damage difference versus heavier weapons will scale. If you include Smithing in your build the difference will be even greater, and if you include Enchanting in your build it will be even greater than that. Also if you incorporate Fortify One-Handed enchanted equipment into your build, a dagger will not benefit from it.
Stealth is not a consideration for a dual wield build. While it still it may help with your overall build, a dual wielding build addresses straight melee combat not stealth attacks.