My first artifact ever was a very simple, no-nonsense, 2400 db siltstone bed menacing with spikes of siltstone, ironically named The Diminshed Calm. Even though i always imagined the spikes on artifact beds to be on the sides of the headboard and not on the frame,.. yet, who knows, they could be anywhere.
Then there's Ustosdolush, Angryborn, a iron battle axe worth 104.400. I kinda imagined the smith forging it with some hidden revenge thoughts on mind. He was one of the original seven, and his mood happened something like 20 years after the foundation of my longest lived fortress. Plenty of repressed rage there.
Carnalcolumn, a limestone mechanism, 10.800 db. I'll spare you the jokes.
Probably the best should be Kurol Ashok, the Embrace of Time (1.610.400 db), an adamantine battle axe. Sounds nice in both languages, even though it seems a huge euphemism for 'axe, meet face', i really like to read in legends the occasional 'so and so was struck down with the Embrace of Time'.
There's another artifact adamantine axe that i consider its twin (similar value, way less interesting name), with an image of the dwarven god of death in goblin bone, contemplating. I'm waiting for an ardent worshipper of him to become a champion to use it, should make him/her happy, in my mind.
If we're talking about sheer value, my best artifact must be Headdissolved the Split Chapel, a raw adamantine mechanism always from the same fort, 1.885.200 db. The name seems a hint to its use.
But what i personally consider the best, it's this simple, 1200 db warthog bone cage, named Thinnedprisons the Dominion of Dimensions. The name is just ridiculously perfect.