Google appears to be the worst of the major search engines from a privacy point of view; Ask.com, with AskEraser turned on, is among the best.
The best way to preserve your privacy is to use a search engine that does not keep your logs in the first place. That's the approach used by Startpage and its European parent company, Ixquick.
NoScript is probably the most important privacy tool, but it costs you in convenience.