Artifacts should be really hard to get, most of them not directly quest related but found using hints found in books and other references.
Some artifacts should not have any clues at all, and should be stumbled upon by coincidence.
This should also be the case with the most rare armor sets, like the daedric armor in Morrowind.
This.
As for what artifacts I want to see return: Merhunes Razor, The Savior's Hide, Daedric Crescent Blade, Masque of Clavicus Vile, The Mentor's Ring, and many more.
I would be surprised if the Fists of Randagulf did not return as they have some significance in Skyrim
Randagulf of Clan Begalin goes down in Tamrielic history as one of the mightiest warriors from Skyrim. He was known for his courage and ferocity in battle and was a factor in many battles. He finally met his fate when King Harald conquered Skyrim. King Harald respected this great hero and took Randagulf's gauntlets for his own. After King Harald died, the gauntlets disappeared. The King claimed that the Fists granted the bearer added strength.