Firefox is my union representative. They are better able to fight for my interests against Google than should I go it alone and use Chrome.
Its not a perfect system, but it should somewhat work.
But many of us who used it from the start think it was a much better browser before. For a long so much was sacrificed for next to no improvement.
For me it was more or less rock solid at >800 tabs and with a lot less memory and more exciting extensions than I have now.
I admit this wasn't everyones experience, but as a superuser tool it has degraded a lot over the years.
That said it is still the best browser for me: I don't think anyone else except Orion (which is Mac only) has actual tree style tabs (not to be confused with vertical, non indented tabs as seen in Opera derivatives).