Camino was the Gecko engine from Firefox in a "proper" Mac UI (unlike Firefox at the time, which was their cross-platform XUL UI). I used to use it as my primary browser and I really liked it.
What killed it was Apple launching Safari - which didn't use Gecko, but instead used KDEs QT-based HTML engine. They named it Webkit, Google later used it for Chrome - then forking it - and leading to the situation we have today where the two QT-derived engines (Blink and, because of iOS, Webkit) dominate.
Personally, I still use Firefox, mainly because I would like there to be another option, but I also use Safari (and I quite like the colour in the header thing).
[1] https://daringfireball.net/2021/10/the_tragedy_of_safari_15_...