Yacy is probably the best followed by Searx although not if you're on Whonix which makes the usage of Yacy (and I'm guessing Searx too) insecure. If you aren't on Whonix and you want good results, you could locally host your Searx instance and adjust the search targets to your liking. This would also be your most private choice since it's

• open source and you don't have to trust a website to actually deploy what you advertise
• you can route it over Tor (alas, I didn't check how) or just morty which will sanitize your searches

P.S. Yes I know Searx is technically a metasearch engine, but hey, it gets the search done.