Google is, by far, the most popular search engine on the internet, and with good reason. It take everything that it's main competitor Yahoo does, and turns it on it's head. Google doesn't try to make it's advertising dollars on the main page, which is fantastic. When I open up a search engine, that's all I want, not a bunch of pictures and hyperlinks to stuff that I don't want or need. The clean page, with the fun brand name change ups, makes the site feel more inviting, it feels like home.
I'm also a big fan of companies that treat their employees fairly, and conducting themselves in an ethical manner. The fact that Google has remained in the top 5 companies to work for for over ten years, and gives their employees 20% of their work week to work on things they are passionate about speaks volumes for the way they view their staff. "Don't be evil," if only every company had that mission statement.