As a Mac guy, I switched back to Firefox when Chrome became practically unusable (slow, crashy). Pleasant surprise: Firefox is snappier and much-evolved since I last used it. Haven't tried DuckDuckGo yet, but I know my day is coming.
This makes no sense. I, like many people here use a Mac and Chrome and can't remember the last time it crashed. I suspect this is something specific to your installation, possibly a rogue plugin you've installed. My experience is quite the opposite to yours. neither ff or chrome crash much, and chrome is significantly faster.
FF, on the other hand, is faster (!) and doesn't crash often.