google is by far my fav. I still use yahoo from time to time, but never on my own computer because Firefox has the google search built in, and when I used IE I had the google toolbar, so it just makes things easier to use google for me atleast
I like Google, but I installed a new search engine recently called blinkx. Apparently it uses a new method of searching (I think) and also searches local documents. Haven't tried it much though.