Sunrise!
Spend a couple of days and nights walking in the woods, and you'll understand why. Also, I like being out on the time of the day when the world wakes up. Seeing the relatively empty streets in the pale morning light, the smell of dew as the morning fog vanishes, the first early birds getting to work, the general silence and increasing liveliness of an ordinary morning is quite awesome. That is, if you're awake enough to be out at that time.
EDIT: Should also point out the effect a winter in the Arctic will have on your mind. I remember the first day of sun this year. That's an experience I'd like to share:
As some of you might have heard too many times now, I was in the military at the time. The days up to February 20 had been icy cold, as the sky was clear all the time, and it had begun to be lighter as well. Several days in a row, we had seen the nearby mountain tops illuminated by the warm glow of the sunrise/sunset (the latter happening immediately after the former). The day in question, our battalion was having a field exercise, and it was a slow day for us supply guys. We had been told that we wouldn't be attacked or anything on that exercise, so all we had to do was keeping the stove alive in the tent.
The reason why there would be no attacks was that the "enemy", the Service platoon, were busy back in the camp. The barracks had received a new set of matresses, and Service were the guys tasked with tossing all the old matresses into a garage, and putting a new matress in each bed. However, the Captain didn't want all the matresses filling up the garage, so we were tasked with moving them to the waste processing plant in Finnsnes, some fifty kilometres away. Some time before noon, six of us privates and three trucks drove back to camp (no superiors). We spent almost three quarters of an hour stuffing the trucks with matresses inside the garage. Then we were ready to go. I was sitting in the first truck, so I was tasked with opening the garage door so the others could drive out. As it opened, I noticed light was cast on the floor. The other guys did as well. Everyone jumped out of the trucks and truly basked in the sunshine. The sun had just rose above the mountain ledge in the field firing range. We stood there for almost ten minutes before driving off. It was a wonderful day. As soon we left the valley where the camp is situated, the entire area was clear. Snow on the ground, silver-coated trees, blue sky, sunshine, and we had the com-radios for ourselves seeing as we were out of range from the exercise. After a job well done at the waste plant, we bought some burgers in Finnsnes, and sat in the trucks watching the sun go down before joining the exercise again. It was the first day we had seen the sun up there since October 20.
Definitely sunrise.