It is only about what medium you are comfortable in. If you have a problem typing on the keyboard or just slow, then you should take paper-based. The only difference is the medium through which you attempt the IELTS exam, there is no other difference between paper-based IELTS and computer-based IELTS.
Students assume that both versions of the IELTS exam are different and think that the content varies too. Test length for both paper-based and computer-based exam is 2 hours and 45 minutes. The scoring pattern is also the same for both versions of the IELTS exam.
For a paper-based exam, you have to manually write/mark the answers on an answer sheet with a pencil, whereas in the computer-based exam you have to use the keyboard to punch in your answers on the computer itself.
The benefit of computer-based IELTS is you don’t need to count the words, the computer will show you the word count. It is also easier to edit, you can cut, copy, and paste. Although, your typing speed should be adequate.
Keep in mind that, there is no difference in the Speaking section as in both cases, the speaking test will be conducted one-on-one by an IELTS examiner.