•
It's free.
•
It's very common in industry.
•
Support for most programming languages.
•
Many applications and libraries are developed natively for Linux.
•
Linux has a better command line.
•
Very easy to knock up quick scripts in Bash.
•
Linux has better package managers that help a lot. Need Python installing?sudo yum install python. Need a compiler? sudo apt-get install g++. Dependencies are managed for you with some intelligence.
•
There's many different distributions of Linux so you can find something that suits you.
•
Linux feels better for development. It gives you the option to choose an environment that suits you and your workflow. It's not a single operating system as the different distros can work differently and can be tweaked based on personal preferences.