Marginalia is interesting because it attempt to search non-commercial contents. this might unearth some contents you can't find on google. If you search something on google and the result is full of spam or ecommerce product pages, try the same keyword on marginalia. Unlike google, it's a keyword search engine, so keep in mind not to ask question in it, but put the keyword that might be included in the content you want to search.

Kagi is a paid search engine. it does use data from other big search engines, but apply its own weighting and filtering and unearth contents normally buried on the big search engines. There is a free trial account if you want to test it yourself to see if it's better than google for your use case.

There are also various searxng instances. searxng is an opensource meta search engines, which uses data from other search engine. Each instances may be configured differently, so you might want to test some of them to decide which instance works the best for your use case.

Some interesting comparison: https://danluu.com/seo-spam/