Windows :
1. Lower hardwear Requirements
2. Safety and security
3. Speed
4. Compatibility
5. Interface and desktop
Unix:
1. Multiuser System
2. Multitask System
3. The Building-Block Approach
4. The UNIX Toolkit
5. Programming Facility
Linux:
1. Open-source
2. Free
3. Customizable
4. Security
5. Stability