TLDR: Don't use Startpage.com for search, use Qwant or DuckDuckGo as your default search engine on your desktop and mobile browsers.
Back in March I recommended that everyone use Startpage instead of Google as their search engine, but I'm now advising people to move over to Qwant or DuckDuckGo.
After a week of testing both privacy-focused searches, I seem to get better results with Qwant, so that's what I use. (Although while writing this, I was experiencing timeouts and 504 errors on Qwant for about 30 minutes and had to use DuckDuckGo. Nothing is easy these days.)
We're entering a phase of search engine diversification, so I'm not sure there's a single 'best' option for everyone anymore.
What Happened?
In September, Startpage announced that System1, an advertising company, had made an investment in their platform, possibly a majority stake. The privacy community was upset, to say the least, as the business incentives for the company no longer seemed to be aligned with those of its users.
On top of this, a recently resigned Startpage consultant and privacy advocate, Liz McIntyre had a fair-but-not-reassuring comment on Reddit: "I have resigned from Startpage, but I'm told privacy will remain in place. Never take this for granted, though. Ongoing public scrutiny is important."
Of course Startpage claims this is no big deal and that the investment was actually by Privacy One Group, which is "a separate operating unit of System1, focused entirely on user privacy."
But all we really have is their word to go on in the face of mounting concerns. If you're interested in the back and forth, here are some links to check out:
Restore Privacy No Longer Recommends Startpage
Discussion of Whether to De-List Startpage From PrivacyTools.io
Startpage Answers Questions on Reddit AMA
User Finds Tracking Script Running on Startpage and Sending Data to System1
Startpage Search owner changes raise serious questions
Techrights.org Really Hates Startpage (listed because you may find these articles interesting, not as an endorsement of Techrights.org's views)
What to do?
I've already spent way too much time worrying about what search engine I use. It really shouldn't have to be this hard to find one that works as most people think it should: Show me what I'm looking for and don't know anything about me.
I've been testing Qwant and DuckDuckGo for the past week and slightly prefer Qwant. They're based in France and seem to be backed at least partly by Bing results. (See also: DuckDuckGo sources)
It still comes down to trust, however. I may be updating you soon on how Qwant and DuckDuckGo are just Russian goofs to try bring down democracy. But we have to do the best with the information we have, so hopefully you can benefit from my hours of wasted time worrying about and researching this.
For now I'm choosing to believe that these privacy-focused search engines can make decent money by selling ads related to search queries and not the personal info of the people doing the searches. Since they are explicitly trying to get users by selling themselves as privacy-first, their business incentives are aligned with actually making that true. A breach of that trust would cause an exodus of that service (cough ... Startpage ... cough) and hurt the business.
If you have a better option or know something I don't about any of this, please yell at me on the discussion page. Or Reddit. Or Hacker News.