I honestly don’t see any reason why we should look into more web browsers while the Tor Browser exists. It is legit the most private of all.
Joke aside, SearX does offer some bad points that could make someone, prefer using other ones, such as the features (Quick answers, Shopping/News integration and for Qwant, Music & Video Games info integrations), the need to give trust to a few or single individual instead of a company with legal obligations (You may say that you prefer an individual than a for-profit company to handle your data, but this goes for preventing any single-individual that could create a backdoor or breach their services for malicious intent), as well as constant maintenance, even if not self-hosting it (Public hosted instances aren’t maintained by people who are on it every hour of the day, some have other preoccupation and jobs).
Those elements also apply to plenties of other categories of services and applications listed on PrivacyGuides.
Either way, this argument should be reserved for its own thread, as it is out-of-topic there.