I'm gonna be a smartass and say that it's the ability to create anything. My first creation is Skadi so I can give her a kiss

But if that's too boring I'm just choosing teleportation

invisibility because im a pussy

Immortality; I wanna spend eternity spending time with my partner, exploring the world at my own pace, seeing what Earth has in store for us next.

communicate with animals so i can talk to any stray kitty i see and chill with while also being able to tell every single fucking annoying loud ass bird in my area to fuck off

Rewinding time
So I can know my exams' content lol

i'd rather not think too hard about things like this so i'll go with teleporting