For street photography, image quality is at the bottom of the list.
For product photography, 35mm Leica lenses give less image quality than I have on my LF product slides. I mean, it's not possible to say such brand has great IQ, but we can say such brand has great IQ for this kind of photography compared to that brand... The truth is, when you shoot handheld, most lenses from most brands won't stop your marvelous photograph from being marvelous, and your marvelous gear won't help you a bit in that...
So, image quality is a too ethereal concept... I've seen great images -for fashion- done without tripod on a 35mm camera, being preferred as final pick to other MF & tripod shots just because the photograph on 35mm was better, even though it was not only less sharp, but even a bit blurry... People don't say "hey, what a sharp image", but "beautiful photograph"...
The answer IMO is image quality doesn't matter 99% of the times. In the other 1% is Ansel Adams and other people who prefer to make technical aspects of photography and even printing the vital part of their photography. And even of the word photography!
F i l m means fun!