1. Windows
1.1. Pros
1.1.1. Compatible with most computers as it covers those using both AMD and Intel processors
1.1.2. Windows has been the most popular operating system available for many years primarily because of its compatibility with most computers as it covers those using both AMD and Intel processors
1.2. Cons
1.2.1. Security issues that Windows faces may discourage some
1.2.2. Microsoft has failed badly with the tablet industry as it is missed out on getting its OS onto the devices because of a lack of support
2. Mac OS X
2.1. Pros
2.1.1. OS X does not require you to put in code in a terminal to get some applications and to get them working
2.1.2. Apple tends to be the best as far as customer service goes
2.2. Cons
2.2.1. OSX is only compatible with Apple Mac computers officially
2.2.2. OS X requires luck or some knowledge to use all the basic features
3. Ubuntu
3.1. Pros
3.1.1. Capable of viewing as many window as you want on a single screeen
3.1.2. Comes with some applications such as photo editer
3.2. Cons
3.2.1. Ubuntu is about 2 GB where as both Windows and OS X is much bigger
3.2.2. Coming to multimedia, DVD playing capacity will not come with Ubuntu