This search engine is the best I've encountered to date. The searching interface can be simple or as comprehensive as required, and in either case, the process is very efficient without excessive ads.
You can tailor its advanced search engine capabilities to accommodate a wide range of information acquisition requirements.
A nice search feature is that ads are limited to three at the top of a search results page and two at the bottom.
In addition, since I work in the multiple languages, the ability to switch from one to another is convenient. The site supports most Indo European languages plus some capability for Oriental and Asian forms of expression.