WhiteHat Aviator is probably the most secure browser, built with security and privacy in mind from the bottom up. At the moment (March 15, 2014), you can only download it for an Apple computer from their website (https://www.whitehatsec.com/aviator/). Technically, it is in beta (testing), but it seems to be fairly reliable. Once installed, the settings automatically disable tracking cookies, caching (storing), and history. The search engine within it is DuckDuckGo, which is also heavy into security and privacy.