I've been on Firefox on and off for most of my life. Was using Chrome predominately until last year, and went to Firefox. Firefox is great - I find it to be an absolute 100% quality replacement to Chrome.
DDG has a few shortcomings, and is doable to replace Google but it is not as good. I also feel DDG is like an 'uncensored' engine, Google has so many censors and manipulations on their queries, anyone anti-censorship/manipulation should not use Googles search engine
I'm currently using Google though, so shit, I'm a hypocrite