My preferred choice. Unlike Google it doesn't track you (or at least DuckDuckGo claim it doesn't). The search results aren't quite as complete as Google's, but they're pretty darned close.
On Windows, one of the Antivirus packages pops up and says something like 'Our customers have reported DuckDuckGo to be unreliable. Would you like Google instead?'. This appears to be a marketing ploy: I suspect 'our customers' to be, ahem, Google.
Best of all, when 'the Microsoft Security Centre' calls, they've never heard of DuckDuckGo. When they ask you to Google things, you truthfully tell then you don't have it, and their scam patter goes all wobbly…
Dave