Normally for short term projects, manual testing is the best. Because it may take long time to learn the tool and implement it.
For long term project or ongoing projects, automation is the best since the script are reusable. So the same script after doing some alteration can be used further.
I am fully agree with Saritha's reply. Actually manual testing gives you quick result whereas to automate an application takes much effort. You need to be expert in tool and scripting then your application should be stable and after that if you are able to do the scripting then it will come useful for next version. Whereas Manual testing just need to study the requirements and learn the application and testing on it.