It is like looking for employment.

Some employers like humorous and creative cover letters.

Some employers only read the cover letter, and throw the resume away. Some employers only read the resume, and throw the cover letter away. Some of them will only look at your soft skills. Others will only look at your experience. Still others will decide only at the interview(s).

Of coures you need to have a presentable application.

But in general there is no way to predict how they will evaluate you.

But if you want a good job: Be genuine, be honest, be respectful, and be yourself.

And please keep looking even when you are rejected.