Pretty happy with what mine is offering now. I also have a few nice ones I don't leave in; for example a -11 forest expansion cost, two -6 library tech food costs (and a -6% gold, but I'll probably dump that one at some point... I'm always full of gold). Also I have some very good armour & weapons where I need to open later slots, one is -6% to basically all attackers (including heavy cavalry hitpoints, fighter hitpoints, paratrooper hitpoints & etc), and my favourite (but not yet equipped) is +1% oil looted, but both slot 2 & 3 are +11% oil looted.
I wanted to point out that there is no point using Vault capacity at this point in time, it is based on Enlightenment level Vault, so if you have +20% capacity (which I have if I want) you actually only get a paltry +4% if you are Atomic with all upgrades. Really not worth it. The capacity I have in an artefact is only a side-effect of an increase in vault interest (which is good!).
Also Guerrilla Damage is anoter side effect, I dont think I've ever been attacked by a Guerrilla...
I wish there was some way to determine how many museum items I've creafted, would have to be over 100 now, perhaps 200 (or more?).
The boosts I most seek are:
* anything that helps oil production or looting
* defence against fighters, general HPs, heavy cavalry HPs, raider damage