Diomidis Spinellis has written a good paper for the "30^th International Conference on Software Engineering" (ICSE '08) that looks at the code quality of the source codes of Windows (WRK – Research Kernel based on Windows Server 2003), Linux, Solaris and FreeBSD. Diomidis has analyzed the source codes of these 4 kernels and uses some code metrics, in order to measure the quality of each kernel in each area.

For those, who don’t like reading lengthy texts, a summary of the results is at the end (section 5: summary and discussion). Each operating system has its own strengths and weaknesses, so there is no clear winner.

View: A Tale of Four Kernels | Full Article