Oracle Database Discussions

I know there's not a direct comparison and this is more of a subjective type of question, but does anyone know of a document or some type of guidance on when to use Oracle vs. SQL Server for your applications. I have a list of questions (and answers) that would lean someone one way or another, but wanted to see if a someone (Gartner, Forrester, etc.) had done any research and developed a loose guideline for when to use which database, so I didn't have to completely reinvent the wheel.

Thanks,