Unarmored: The best mobility, at the expense of any protection. (Linwe's Hood, or the Ancient Shrouded Cowl with Gauntlets of the Old Gods.) While it's possible to find it randomly enchanted on heavy armor, or disenchanting it (Not from any of the peices I've mentioned) to make your own, it's extremely unlikely, and/or a lot more work than just doing the Dark Brotherhood, and Cidnha Mine quests. (Shrouded Cowl, Ancient Shrouded Cowl, Linwe's Hood, Krosis, and the Gauntlets of the Old Gods.) All of them are Light armor, and certain sets can boost every shot's damage by nearly half. There's several armor peices that come with this enchantment scripted in the game. The real reason why Light is probably your best bet can be summed up in 2 words: Fortify Archery. This means stress mobility over passive protection, that's your defence. As an archer, your primary goal is to stay out of the Melee as much as possible, because that's where you're weakest.

Light: The classic choice, doesn't slow you down as much, you can sneak with it (Not as critical, because you just have to get within Range undetected) and the Wind Walker perk really helps with Stamina a lot. If you're doing an Arcane Archer (I.E Bound Bow) then Vokun, and the strongests boots/gloves you can get around Robes of Conjuration (Master when you can get them) is a great outfit. It can be done, but you pretty much have to build around minimizing the penalties to movement, and stealth. I've tried just about everything, so I'll run through the list with the reasons to make your decision easier:

Skyrim se archery mods