Which artifacts are best to equip a hero with?

In general, I don't even throw out junk from my hero's bag (we always carry everything with us).
Before battles, I equip artifacts that protect me as much as possible and deal damage to the enemy (I don't mind changing into different gear every time)...

That's for sure. All artifacts will come in handy. Fortunately, there is no limit on how many you can carry. In some RPGs, there are penalties (for example, the hero moves slower, etc.). So the developers could take note of this fact. But it's better if they don't :)

I've noticed that I get more pleasure from fighting for artifacts than, say, for resources or knowledge...