I switched to using DDG as a default a long time ago and have experienced improved results over the last few years. I would say that ~97.5% of my searches now go over DDG, if the search fail I add "!g" to the query to see if Google can do better. About 40% of my searches are research related, 40% software development related, and 20% "others". Searches that tend to fail are usually for local news in my country of origin or very exotic configuration/library errors. For the former, Google still does better than DDG, for the latter, it is about 50/50 if Google will fail to deliver as well.