This is actually such a hard question, I have so many "well it depends on..."
So this is my assumption: if I could instantly be the best at something, and I could benefit off of this talent immediately and I wouldn't have to exert any effort to give myself exposure or media attention, I would want to be best at an instrument (probably bassoon, because that's my main instrument).
I would then just travel the world playing baroque bassoon sonatas effortlessly to crowds across Europe (because I would yeet from the US as fast as I could if I had such an opportunity).
hehe