My personal rule of thumb is that if I look for a reference manual or an official website vanilla DDG is the way to go. If I'm looking for really fresh contents like news or latest QA !g gives better results.

Guess it's logical because even if the search algorithm of DDG is pretty neat, they can't compete yet with Google army of crawlers that probably use every idle computing power of their massive cloud.

The key for me is making the query _slightly_ more descriptive. It's a good thing that it's not tracking me, so it's fair enough that I should type a bit more so that it knows I mean Ruby the language and not the gemstone.