I personally recommend VMware Fusion to run for your virtualization needs.
Alternatively, you can use Windows 7 or Windows 10, though there’s nothing in Quicken’s software that needs the latest version of Microsoft’s operating system. Though Windows 8.1 is stable, well tested for security, and has many more years of security updates.
There are two reasons why I do this: Let me touch on the second reason in a little bit more detail.
The added benefit of virtualizing your personal finance software is security.
Not compatible with Safari 5 on Mac OS X 10.6 or 10.7) For full compatibility information, see this article.
Running Quicken on a Mac has been a frustrating experience.