Go in the direction that is pulling the hardest, but you have interest in the outdoors and a desire to hike the AT. A distance hike can be an education in itself if you pay attention to your environment and yourself. You'll most likely mature and be able to take care of yourself because of the hike and you just may seed an interest in some outdoor related activity you can pursue in college that you wouldn't have thought of otherwise. Lot's of people head off the the military right after HS. The choice between the AT and college is pretty mild. Wish you the best in your decision!