This needs to be repeated because it helps to understand the issue.

There are only four (4) search indexes of sufficient size in English, these are Bing, Google, Baidu (Chinese), and Yandex (Russian).

Everything on the internet that calls itself a "search engine" gets its search result data from one of those four indexes. Different front ends provide different features around the results, whether it is privacy enhancement, ad enhancement, Etc.

Google's English language index is generally considered the 'best' based on the depth of the index with respect to its crawl size and that index's ability to provide both good precision and recall.

You can use any search site you want but you will likely be using Google search results. If you feel like you're results aren't quite as good as Google's, and you are in the US, you are probably using Bing. Neither Baidu nor Yandex have US data centers so latency to their indexes is pretty bad for most front end web sites.