The easy answer is both as these are the times of day when the sun is low in the sky and the light is golden. That said time on Maui is precious and I know you want to make the most of it. For those people that are planning to go to Haleakala for sunrise, doing a sunset workshop makes sense as you will experience great light in both activities. If not going to Haleakala, but traveling with kids, friends, or family getting away for a sunrise is easier than a sunset. For sunrise workshops I go along the road towards Hana or south to Makena. For sunset, I prefer Kihei, Makena, and Wailea. Each workshop has its advantages. In the morning there is no traffic and few people around and at sunset the shoreline is bathed in golden light. Sometimes after setting the color pops, making for surreal skies.