Your entire post sounds like something one of my developers would type out after spending a half hour trying to figure out how to install a new piece of technology. As I tell them, your issues are probably due to a misconfiguration issue.
I use Firefox personally day to day and have very little issues with it. I'm going to point by point rebuttal:
Slow, don't know what you mean, I use it every day. Do you perhaps have other add-ons or something running in it that's causing it to slow down or maybe sites that don't work appropriately?
Firefox uses less RAM on average than Chrome, but a lot of your any of the Blink browsers. It is true that it uses less RAM, but there are other builds that are even leaner. I use it to maximize the amount of RAM I have access to on my system so I can run virtual machines in my professional career.
What AI bullshit are they pushing on you? I didn't even know Firefox had AI features. That's how little it bothers me and how little it actually comes up.
If it's crashing constantly, there seems to be a problem with your setup and not necessarily the technology itself.
Yes, their ad model is annoying, and the fact that they have ads to support themselves suck, but they have to make money somehow, and nobody else is paying for it
I don't relaunch my Firefox and use it to the tune of 50 plus tabs for 30 plus days straight with little issue. The new integrated sidebar tabs make this really nice.
I've literally never had the restore previous feature never not work for me, but you could also just install a session manager extension of which there are many if that's not good enough.
I will fully admit, profile management is a total wreck on this browser, so I won't actually complain about that point.
I'm not sure you should use any alternatives. I'm not entirely sure you can handle a browser correctly. However, I think Vivaldi would probably fit many of your pain points along the company embracing anti-AI.
Careful though, I think they have ads somewhere on their site too to support their browser.
Link to blog:
This is a really nice response, OP, you should listen to what this person has to say.