I still hate the fact that different browser profiles and profile switching aren't surfaced like they are in Chrome. I think it's such a major use case for modern web browsing, I find it hard to believe they aren't prioritizing it. (FWIW this isn't even supported in Safari, which I would have preferred using)
I still keep it around because I love it's download manager, but I tend to use a lot of Google services, and out of habit, I stick to Chrome.
(ps. I was an early Chrome adopter, so it's quite sticky with me)