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.
The morphing cube (or Escafil Device for the initiated) from Animorphs still has a special place in my heart. Nerfs for the sake of narrative tension aside (notably the 2 hour time limit), what a cool piece of tech that empowers people:
Only one use needed for any individual, the device itself seems to have unlimited uses, and you only need to touch it for a few seconds for it to permanently give you abilities!
And what abilities they are! Copy any living animal’s DNA by touch, morph into an exact copy of any animal whose DNA you’ve already acquired, and heal all physical damage each time you morph while expelling any foreign bodies from your own (someone is even canonically cured of rabies via morphing).