About the best outboard motor I ever remember for a canoe goes back (hate to say it) over 55 years ago ~
And that was a 3/4 hp Neptune. I don't think the tiny thing even filled with gas weighed 18 lbs! But it would putts a canoe along just a tad above paddle speed (wide open) and not upset the balance of things that much.

Today I use a transomed Raddison (not to be confused with a square back) as my back into the boonies fishing boat. Most usually I paddle the thing ... not as smooth a paddler as the real thing, but I can hang a small outboard or an electric motor onto it for some larger streches of water. I like using my 3hp Evinrude the best but never at full throttle, maybe about half. A friend has a 2hp Evinrude and they look almost identical and produce about the same speed for a little boat. One big difference ~ the 3hp has the "shift" (really a clutch), where you can start the thing in neutral, get yourself and everything all settled and then gently drop it into forward gear. Makes a big difference for a small type water craft.

Dale