I’m not sure anyone claims their reason for not using Firefox is that they think Google is a better organisation than the Mozilla Foundation.
I agree that browser diversity is a good thing for the web, and I’d love it if Firefox was more popular. But I’m not going to let that motivate my reasoning about whether it’s a good web browser.
That depends - is software quality, especially security, a relevant part of "better organization"?
I want to use Firefox, but when I use it, mobile or desktop, I notice a lot of page-induced crashing bugs or severe rendering errors (e.g., things that absolutely look like pointer discipline issues, blocks copied into the wrong area, etc.), which makes me extremely uncomfortable using it, as those crashes may be exploits in waiting, and there are a lot of them.
I agree that browser diversity is a good thing for the web, and I’d love it if Firefox was more popular. But I’m not going to let that motivate my reasoning about whether it’s a good web browser.