Do you want to go touring or take advantage of white water rushing down a stream you need to choose the right paddle.
A great way to figure out the length, sit about 6 inches off the floor. Add the length from the floor to your nose and add that to the length of the paddle and the wider the canoe the longer the paddle. If you are touring you want it to be light and flexible. White water you want the paddle to be strong and stiff.
Wood is popular because it flexes and absorbs shock well. You can choose from hard wood or soft depending on your budget. Light sanding and varnishing to maintain the wood. Fiberglass is light , durable and maintenance free. Economically the aluminum shaft with a polyethylene blade will do the trick.