There are 3 different versions of the QL-17. The original version is rather large and clunky. The second variation was smaller and more modern, the third variation was the GIII, which is more or less identical to the second version.
When looking at old Canonets, check the glass carefully, for some reason Canon glass is exceedingly fungus-prone, check both the front and rear elements. I have 4 Canonets sitting on my shelf, one is a plain Canonet, one is the old QL-17, two are the newer black QL-17 cameras. Both of the older cameras have fungus in the lenses.
The entry-level rangefinder I would prefer to the Canonet is the Yashica GX or CC. The Yashica cameras do not offer the manual operation that the Canonet has, but in my experience they are capable of better quality images. The Yashicas are somewhat smaller, simpler to operate, and easier to maintain (such as when you want to remove the lens elements for cleaning, or the top cover to clean the rangefinder/viewfinder).