One I just recently discovered is symbolhound.com. It's nice because it lets you search for characters that google absolutely refuses to treat as search terms. I needed to debug some makefiles and bash scripts the other day (not my strong suit!) and it helped me understand some of the weird syntax I was seeing.
As others have mentioned, Google no longer respecting literal search terms has made it much worse for many types of searches. DDG had been great at this, but sadly has been following in Google's footsteps the past few years.
You too eh? Over the past decade I've gone from loving reddit to actively avoiding it in most cases, but if I'm looking for specific info on a niche topic, adding "reddit" to a search is often the only way I can get real content written by and for real human beings instead of SEO spam.
Sinister twist though: the SEO crowd has gotten wise to this. I've noticed recently that they've started throwing "reddit" into their spam as a random keyword.
I absolutely hated when they did remove it. I was able to sort of mitigate it by adding "forums" and "discussions" to search terms but it is not the same of course.
If I ever X vs Y in google, I append site:reddit.com
I'm not a huge fan of Reddit, but it's about the largest forum. I really miss Forum search in Google.