Composition. Ultimately, that's what it comes down to for me. I could have perfect exposure, tack sharp focus (which is something that isn't exactly a priority for me anyway), stealthy, lightweight gear, even perfect "golden hour" lighting, and yadda yadda yadda, none of that matters without being able to see the picture that you want to take. On the other hand, you can have a technically-inferior shot that is memorable and timeless if you have the right eye for composition and are able to tell your story through that composition.
The other choices are skills that I could practice and become expert in, or gear that may or may not help me accomplish my goal. But composition...yes, it can be learned, but to go beyond the textbook rules and find the shot that is composed perfectly even if it breaks all the rules? That's a talent, not just a skill, and I'm not convinced it can be learned. I think you have it or you don't.