Not ever had Firefox for android be slow and buggy for myself! I've been using it in place of chrome on my phone for a good year. Honestly everyone keeps talking about how FF is "slow and buggy" and it has NEVER given me issue :/ why is my subjective experience so different to your subjective experience?
Meanwhile chrome/chromium is the one which is most likely to cause me GPU driver crashes, but that's because I use it for fun VR and "let's see how big I can make textures" experiments. Generally it manages a higher frame rate than FF in that context with stability as tradeoff.