This is actually very tough question. Here are my thoughts:
I know for sure what Google is full of word-filters, shadow-bans etc etc. The last benchmark which amazed me much was "left wing terrorism" when Alphabet blatantly pushed their agenda onto me mixing-in rare violent rightwingers into the what they called a «search results». I remember the old days when Google just started counting clicks and got criticised for shaping the results to the user interests. Now its not the case, the only correct interests is Big Brother interests. Also, Google DE and Google FR pages were inciting mostly peaceful riots. Definitely no go.
Also, I totally don't get why yandex.com got on the list, it is fully controlled by Terrorussia and their midget tyrant. BTW, my observation are that their image search censors different things than Goo, but such swamp-to-swamp is hardly suitable for everyday use, like CNN ⇔ RT zapping.
DuckDuckGo... *sigh* DuckDuckGo tries, tries very hard... but fails *sigh*. If there are any censorship there, its well hidden behind the terrible search quality. Also, I've noticed very typical to DDG failures to satisfy exact phrase queries. It is a toy.
I read what Microsoft is really into censorship but don't know if they are extended the policy to web search because their search quality is even worse than DDG's. I use microsoft.com very often, they have 2-3 distinct(!) versions of documentation pages also a terrible link rot, but integrated Bing is not of any help there.
Brave is actually very promising but I'd rather conservatively say what more assessment needed to rate them. Simply too immature to judge them right now.