For PHP/MySQL applications, which of the UNIX versions are most suitable?

For PHP/MySQL applications Unix vesions, suitable can be Linux, BSD, Irix, Solaris, HP-UX, or one of the
other flavors. Most of the people who created PHP and MySQL are deeply involved with Unix, and most of their development is done on Unix machines, so it’s not surprising that the software they have created works best on Linux, BSD, and other Unix boxes.