DDG crossed this threshold for me years ago, and I've been using it consistently since 2013. (With fairly frequent statements to that effect on HN.)

For much of that time the principle justifications were 1) It Is Not Google, 2) results are roughly comparable, and 3) an improved privacy impact.

Over the past year or two, the rationale's shifted: results and most especially experience are markedly better.

Google's polluting the SERP with advertising, bringing to mind the environment into which Google first emerged in the late 1990s, with what many at the time considered a mature search-engine environment, is most especially notable.

My use of console browsers and commandline queries (not a typical use case, though extraordinarily convenient) is another huge factor.

Google is now utterly unusable in console-mode browsers.

By contrast, the default DDG site works, and works well, and the "lite" site is ... amazeballs: https://duckduckgo.com/lite

As a Bash/bourne shell function:

ddg ()
{
/usr/bin/w3m "https://duckduckgo.com/lite?q=$*&kd=-1"
}

As of a few weeks ago, DDG added "region" and "time" selectors to the lite results page, matching the capabilities recently added to the default DDG site. The fact that "lite" not only works but is actively maintained speaks volumes.

The search box is one tab away (it's 12 in Google).

Search results are directly clickable. I don't know what new idiocy has infected Google, but when I view a Google results page in, say, w3m, I cannot click the links:

http://www.google.com/search?ie=ISO-8859-1&hl=en&source=hp&b...

(This is beyond the "the links are redirected for tracking", not the case on DDG with a URL parameter, but Google has broken its own search links.)

I can only assume Google are telling advanced users that they are no longer of interest to the firm.

In a graphical browser, results are crammed with ads and filler, annoying, hard to parse, and quite frequently just not very good.

There are occasional exceptions:

1. For date-ranged search, Google (and specifically desktop) is the only option.

2. Some older content isn't accessible on DDG. Generally this is pre-2005 / pre-2000 content.

3. Some obscure content only appears on Google, though to a vastly lesser extent than was true only a few years ago.

Also, again, DDG's bang searches are hugely useful, with at least a couple dozen in frequent use by me.

The broader picture, though, is that Web search seems generally less useful than it was 5-10 years ago.

That seems to be a mix of far more crap online, as well as black-hat SEO winning over Web search companies (death penalties really ought to be a thing), and far more "traditional" content (books, scientific articles, other published sources) now being accessible online.

I'll hit up Wikipedia, search for references, and follow those, or go to Worldcat and run a subject search, then read books, magazines, or articles directly (through Library Genesis or Sci-Hub), rather than waste my time on Web glurge.

Yes, there are still some good voices out there, but between crap content, crap Web UI/UX, and general web annoyances, it's become a net negative.

AdTech and Surveillance Capitalism destroy everything.