Which browser do you use?

I remember when Firefox used to be considered a "goto" browser so here are my questions.

1. Which browser do you use for your daily driver?
2. Why has Firefox lost so much of it's market share and what's the main issues that's caused this?
3. Is "Firefox" safe to use and are there any reasons not to use it?
4. If you opened any browser in two separate windows then would this have the same effect as using containers …

browser daily driver firefox goto issues lost main market market share privacy questions safe share