DDG is my default on some browsers and machines, but it still lacks a lot in relevant results. I find myself using startpage.com or even Google (the latter for better image searches) very often. The lack of a date based search is a huge disadvantage since I use that very often in other engines.

Lately, DDG has also been quite slow for me and doesn't load at all for several seconds. Overall, I love the privacy part, but it's not as useful as a search engine ought to be for my usage. So I'm unable to quit the other alternatives, even though I badly want to.