Personally, I'd just go with light armor, unless you are RPing a robed mage. You get a hidden 100 AR with real armor over mage armor and it takes three perks to max out mage armor, which you can save and put to something else. If you put perks into light armor, or if you smith your armor, even with no perks in smithing, you can easily get better protection with light armor than you can with mage armor, when you account for the hidden 100 you get with real light armor. In other words, 200 AR from light armor = 300 AR from mage armor.
You will get better stamina regen with light armor with the Wind Walker perk than you will with no armor, and you get your AR protection 24/7 without having to constantly recast. If you are using muffle, it will negate the noise from light armor, so sneaking in light armor is no issue. Once you get Unhindered, which is required for Wind Walker, light armor and no armor movement will be the same. Even before that, the movement penalty from light armor is slight.
The main advantage I see for using robes is the magicka regen enchantment you can get from robes, but a high magicka regen is mostly needed for destruction mages, not sneak illusionists.