What makes the Ngozumpa glacier superior than the Khumbu Glacier?

It’s a general assumption and in everyone's mind that Khumbu glacier is the ultimate one at the base of Everest. But the realistic truth is the Ngozumpa Glacier in the Gokyo Valley is actually larger and more impressive. The glacier itself drains off the face of Cho Oyu and runs 36 km (22 miles) down the Gokyo Valley making it one of the longest in the Himalayas. Off late its lower end it has been melting in recent years and several lakes have formed on the surface of the glacier. Much of the lower section of the glacier is covered by a thick layer of moraine material (rocks) but the ice is still present underneath.