Google is the website I visit the most often, according to both my phone and my computer. I've never once used Yahoo on purpose, but it's not as exciting as the name implies. Google at least had the decency to color their letters more than one color.
I most often use Google Chrome and Google search, but my emails are through Yahoo. I have an email through Google for my YouTube account, but I never use it to direct regular emails to. I think I'm just used to always having Yahoo for my email so I never changed, but I much prefer Google products.
Plus Google does interesting things to their homepage from time to time.
I have always used Google, but only the search engine. Neither one have I used for email or any other of the extra features. As search engines, the two are probably not drastically different, but as brands, Google is the pioneer.
Yahoo does have Yahoo answers, but with Google I can actually get what I'm looking for, which may very well be Yahoo Answers. Obviously my vote is Google.