Well, both places have their futures and beauty. It depends on every trekker's willingness and requirements, Ghunsa is the biggest settlement en-route of the Kanchenjunga Circuit trek with people's unique culture and daily life hood, whereas Khambachen is more option for a day hike and scenery. You may visit the either Jannu viewpoint known as the Kumbhakarna viewpoint (4,400m) to see a breathtaking view of the mountains view especially Mt. Kumbhakarna (7,711m) and surrounding it’s amazing nature or visit the Nupchhu Pokhari (4,942m). So, to explore the mountain scenery, you are suggested to stay two nights at Khambachen/Khangpachen.