For a 5-day expedition for D of E, would canoe or kayak be better?

Canoe! Canoes are best for travel. Five days in a kayak may turn into days of physical discomfort. You can kneel in the canoe or sit in it. You can even stand up and stretch. You don't need to use a single bladed paddle in the canoe. Many trippers carry both a double bladed paddle as well as a single bladed one. It is also possible to use oars or a pole. Think outside the box. Don't neglect conditioning and practice. The voyagers used short paddles that they fashioned each night from available trees.