Yahoo! Became my default Search Engine on iOS
Why? Because Yahoo is the only search engine that properly opens up Apple Maps when searching for directions for a business in Mobile Safari.
Google Search - Click on directions in the search results and will either show you an advertisement for Google Maps for iOS or show you a web app. There is no option to open in Apple Maps and no easy way to copy-paste the address. I'm fine with using Google Maps for these, but I don't want to use Chrome to have the links properly supported.
Bing Search - Click on directions and it opens a web app with similar problems as Google Search.
Seems that only Yahoo! properly supports this important functionality so that is what I'm left with.