It is impossible to say who is stronger between the two brands. They each focus on different areas.
Canon is a camera brand - providing the best cameras, Leica is an optical brand - providing the best optical equipment. This
The positioning between the two is different. If you look at the production, R&D, and technology in the electronic field, Canon is definitely strong (many of the patented technologies of various digital cameras belong to Canon). If you look at it in the optical field, there is no doubt that Leica is strong
(Patents in the optical field are basically divided between Leica and Zeiss).
In short, Canon is way ahead of Leica in terms of digital camera performance, and it is way ahead of Canon in terms of lenses and optics. Leica also wins in terms of the manufacturing process of the camera body. German machining technology is still unrivaled on the planet.