Either is fine. If neutral feels best for you, then go ahead and point the feet straight ahead. But if a flare up to 30 degrees feels better to you, then feel free to flare. Flaring the feet 15-30 degrees feels best for the majority of lifters, and this is a good position for knee health.
However, some lifters with particular hip anatomy do better pointing their feet straight ahead. Tinker around and do what works for you.