Why Google Should Be Your One & Only
When you set out to grab all the traffic the search engines have to offer, you have the simple goal: getting to the top of the Google search results.
What about Yahoo or Bing?
The truth is, they don’t matter. 80% of searches happen on Google. That’s a whole lot more traffic than all the rest combined. There is no reason to waste your time an money on 20% of the market when you can easily grab at most of it in one place. Also, Google has the strictest requirements for quality, so if your site gets to the top of Google, it is almost certain that other search engines like Yahoo or Bing will follow. You can rank for them without trying, just by going after Google. There is really no reason to target them.