Will the canoe be used on flatwater, whitewater, or both? A great flatwater canoe will not be the best in big river rapids. Conversely a great whitewater canoe will not be the best choice for crossing lakes. A flatwater canoe should be more straight keeled to assist in tracking. It should also be shallower to reduce the effects of wind, be narrower and have finer entry lines for speed. A good whitewater canoe needs to have some rocker to facilitate quick turns. They will also be deeper and will usually have fuller ends for a drier ride. If you are looking to paddle on both flatwater and whitewater you will need a canoe with good multi-purpose characteristics.
Will you only be out for an hour or two at the cottage or are you going to go downriver for two weeks? A typical cottage canoe can be small because it will probably only hold the paddlers and a small amount of gear. An expedition canoe will have to have a larger volume to hold all your food, tents, and packs for your entire time in the interior.
If you plan on doing a lot of portaging you need to consider the weight of your canoe. You also need to remember that while you may not portage, you still may need to put your boat on top of your vehicle from time to time. Make sure you can lift it comfortably and safely.
Composite canoes are lighter and offer better glide through the water whereas plastic boats are tougher and are more appropriate where severe impacts may occur. Whitewater canoes will need to be made of more durable materials to cope with impacts. Flatwater canoes can be made of lighter materials for portaging from lake to lake.
As a general rule, lighter canoes are more expensive. While you may have decided that you need a high end boat, the practical matter of expense must be considered.