There are two types of canoes- the type that is "canoe like", marketed for the summer BBQ at the lake crowd, and another type that is designed to perform under a lot of different conditions, including with a load and meant to go places far from the landing.
The first type will only cause you grief if you try to actually do anything with them. The second type are made for folks who go on multi day trips and like to have some adventure anyway. So you will be well served with any number of this type canoe.
Most canoes made for consumers were first shortened versions of longer, proven designs. Eventually that morphed into canoes made to just "look" like a canoe.
That type is marketed to unknowing consumers and usually have flatter bottoms (seem more stable) have a big honking keel so yo don't have to know how to paddle to keep straight. These are shorter in general. Not that short canoes are all poor designs, but you have to know what to look for. A longer canoe can carry more, handle bigger water and is easier to paddle for longer periods. A canoe with a good design 17 feet long is actually quick to turn, tracks straight and can carry you, a buddy, gear (and a deer on the trip back).
Look for a canoe at least 16 foot long with a more rounded or shallow vee bottom section. Though tippy to the uninitiated, this is actually a very forgiving design and has great secondary stability. Something you will appreciate if you get caught out on a lake and the wind picks up. Flat bottom canoes will seem stable, but do not retain that if you tip them very far. They will go over without much warning, don't handle waves very well and without a big keel to keep the bottms flat will oilcan.
A really good way to learn about canoe design is look and read about the old guide canoes. They had to do a lot of things well under bad conditions.
Then apply those traits to the newer designs as a bench mark. There are some pretty good modern hull shapes- Mad River is one example.
The canoe I built was patterned on an 1886 guide canoe. I used it everywhere- flat rivers, big lakes, small streams with quickwater. It had no keel and turned on a dime, but tracked like a dream. It was 18 foot 6 inches long.
Not saying to go that route, but wanted to show how the lengths we are accustomed to seeing as "good" are not really that but just a way marketers tried to keep from scaring off consumers because they usually want a canoe the wifey can help lift or can fit on the Prius. A 17 or 18 foot canoe only seems long until you use it.
Hope this helps.
Joshua