Id personally like literature/imagination materialization. The whole concept of powers not being controllable, manifesting beings more powerful than yourself really appeals to me.
For artifacts the H dial is my favorite. I love seeing different unique powers, outfits, etc. and always liked the idea of following the same person with different powers everytime they tried to use them.
Watching doom patrol and they had two characters with that power, one was off their own art and one was off their mind. Really like the concept, they have like lives of their own and realize death is a possibility, liked that