If you came for the cultural experience and you want to walk a real Tibetan pilgrimage circuit, choose the Sacred Waterfall. Lower altitude (max ~3,400 m), gentler gradient, forest the whole way, and the waterfall itself is a working pilgrimage site. If you came for the photograph and the alpine drama, choose the Ice Lake — higher (3,900 m), harder (~700 m gain), exposed above tree-line, and visually the stronger payoff. Your guide will help you decide on the morning of Day 2 based on weather and how Day 1 went for your body.