In my experience, Yahoo really excels in image search and whenever there are structural changes made to websites (for some reason, Google doesn't really handle

In my experience, Yahoo really excels in image search and whenever there are structural changes made to websites (for some reason, Google doesn't really handle moved websites / pages well - there was even an article about that a few months back). But overall, there is around 90% overlap between the major search engines as demonstrated by multiple studies. That being said, I do feel often like Google's search result quality is decreasing. Bias due to using it exclusively perhaps?