If you want results for your efforts, then what you really need is to understand the most critical aspects of the cover letter. The format is just one aspect. There are more details that you have to take into account. The content is the most essential point you have to bank upon. You might have a very crisp paper with nice format in it but it will not be helpful if you do not indicate the skills and credentials required for a certain job position. Of course, you need to possess the same essential skills, traits and knowledge. Thus, you must evaluate first your qualifications before aiming for the brightest cover letter format.
Overall, having the correct letter format will guarantee people that they can have the upper edge against other job applicants. All they need to do is to keep it clean and unique. There is no need to have a very extravagant cover letter. Just indicate all the essential things needed that can help them to get the job they need.