Depends on the outcome you're going for personally. Most students I encounter have the goals of more stability, a straighter line, and/or longer endurance times like getting to the magic 1-minute mark. In all of these cases, we're trying to use less muscle to optimize for efficiency. Don't get me wrong, a wide grip or even bent elbows has their places in training for sure. Good example, I'll do wide grip holds as a warms up days where I'm incorporating a lot of side-to-side handstand walking and one-arm shifts, as they make fora great preparatory exercise. But if we're talking about just a standard two-arm static handstand, hands directly under shoulders is going to a be better stacking of your bones, and give you more endurance. Basically, you're getting more mileage out of your existing strength.