With that out of the way, lets dive into the best Artifact commanders in MTG
You won't see much milling going on in white MTG decks, but black, green, and occasionally red see a mill card or two
Lightning Greaves [Cat deck]: A great way to protect a cat, and it has zero equip cost
Mirage Mirror was a cool try to get double Colossus that wasnt quite Sanctum of Ugin
Giott, King of the Dwarves As a dwarf fan, this King of the Dwarves is sadly not moving the needle much, although he should be a good signpost for the white/red equipment limited archetype with his rummaging and double strike
The most likely reasons are if it's sacrificed, if it's legendary and another legendary permanent with the same name is controlled by the same player, if it's a planeswalker and another planeswalker with the same subtype is controlled by the same player, if it's a creature with toughness 0 or less, or if it's an Aura that's either unattached or attached to something illegal