I own or have owned most of the cameras mentioned. I've kept my Canonet Ql17L (same size, made in Japan earlier version than GIII), Ql17 GIII, Hi-Matic 9, and Lynx 14e. The HM-9 allows metering in manual and fully auto mode. The Lynx is manual only. The Canonets turn the meter off in manual mode, which is annoying. I take a meter reading with it, then set the aperture from there.
The Olympus 35SP has a sharper lens than most Canonets, but the mechanics are not as good. One spring in particular is "hair thin" and under constant pressure. It breaks, and the camera will wind on without stopping. I managed to replace it successfully on mine with a spring from a Minolta parts camera. The one I put in was heavier made, as the original should have been.
The Canonet Ql17L has a very good lens, sharper than 9 of 10 GIII's that I've used. My GIII is "cherry-picked". The Minolta Hi-Matic 9 lens is first rate. I sold off a Konica S2, also just as sharp. The Yashica Lynx 14e lens is "good enough" at F1.4, much better stopped down a little.