You don't have to use either exclusively. Just pick the one you think is best as your default search engine, and for anything that this 'best' one (by whatever standard) cannot handle, you can still fall back to the other.
For example, DDG is really good at documentation lookups like Java or Python docs. Google is much better at complicated queries (I always struggle for an example, had one recently where DDG was just lost and Google gave the perfect top result, and remember thinking "I should write this down" but I don't think I did...), so I use DDG by default and if I can't find what I'm looking for, I fall back to Google. I don't have to fall back for ~90% of my queries, so that's a significant improvement over using Google all the time.
DDG is horrible at images, and Google Images beats Bing Images. But again, 90% of my image queries can be answered by Bing, so in only 10% of the cases I fall back to Google for images.
> For example, DDG is really good at documentation lookups like Java or Python docs
I've kind of found the opposite.
Because Google knows I'm a developer when I search for libraries etc. they're usually at the top.
For example, if I search for 'express' (the NodeJS package) on Google their website is at the bottom of the first page (just below my local newspaper's website, Paisley Express).
On DuckDuckGo it's 1 from the bottom of the second page.
Of course just a single example but you can see where I'm coming from.
For example, DDG is really good at documentation lookups like Java or Python docs. Google is much better at complicated queries (I always struggle for an example, had one recently where DDG was just lost and Google gave the perfect top result, and remember thinking "I should write this down" but I don't think I did...), so I use DDG by default and if I can't find what I'm looking for, I fall back to Google. I don't have to fall back for ~90% of my queries, so that's a significant improvement over using Google all the time.
DDG is horrible at images, and Google Images beats Bing Images. But again, 90% of my image queries can be answered by Bing, so in only 10% of the cases I fall back to Google for images.