I mainly use Firefox (on both Linux and Android), but I also use Chrome regularly. I wouldn't describe Firefox as buggy or clunky. On the whole, I find Firefox more pleasant to use than Chrome on its own merits—nothing at all to do with privacy or Google.

I do agree that Chrome is more performant on JS-heavy websites, but not so much so that I find Firefox sluggish by comparison. And both slow down significantly once you have lots of tabs open.

I prefer Firefox's tab UI to Chrome's, both on desktop and mobile:

• Firefox on desktop will scroll the tab bar horizontally once you have enough tabs open, meaning you can still see the title of each. Chrome will keep on shrinking your tabs until each is just an icon, making it really hard to tell between different pages on the same site.
• The "tab groups" feature of Chrome on Android confuses me and isn't intuitive at all IMO. Firefox just has a traditional list of tabs, which I find much easier to use.

I also love Firefox's screenshot tool. It's so much nicer than taking a screenshot via the OS:

• It lets you screenshot an entire page even if it's too tall for the screen.
• It lets you select specific elements on the page precisely.
• If you invoke it through the developer console, you can take high-DPI screenshots even if you're using a low-DPI monitor. It'll re-render the page for you behind the scenes.

Firefox also has way better (read: any at all) hardware video decoding support on desktop Linux than Chrome does. Some distros patch Chrome to add that support, but Firefox has it in official builds out of the box.

I started using Firefox on Android because my old phone (Nexus 5X) was very RAM-constrained and Firefox seemed to kick fewer other apps out of RAM than Chrome did. I now have a newer phone where RAM isn't an issue, but I still use Firefox, mainly for uBlock and because it can sync tabs, bookmarks, and history to Firefox on my desktop. It runs just as smoothly as Chrome does in my experience.

This is all my personal experience, though. I have experienced frustrating Firefox bugs in the past that make it crash or freeze, and it sounds like GP is currently experiencing one such bug. But I've used Firefox for over a decade and probably only encountered 3-4 such bugs. Each time, once I got frustrated enough to go digging, I found an existing upstream bug report describing the root cause and a workaround to use until a proper fix landed (usually within a couple releases). I've used Chrome a lot less regularly, so I don't know if the experience there is comparable or if they do just have better QA for bugs like that. Either way, I think the benefits of Firefox for me outweigh the occasional bug that gets through for a few releases.