What is the best decision to make when you don't like your job?

Resign to do the company and yourself a favor before disrupting any ongoing business process.

Find yourself, acknowledge what position you would like to reach, find a job, and achieve your life goals.

Saying try another job is easy, but it is not always feasible.

I feel in this situation the best decision is to look back and see why are not likig your job.

Are you doing it wrong?

Are there areas you can improve on?

What are the skills that can be gained in your current job?

What is the part that you enjoy in your job and is there a way to build up on that?

If all of the above anwsers lead to the ultimate decision of leaving the job, then seriously consider leaving the job and do something that you like.

First find the job you really like in your field 

Do make sure you give whatever time frame they told you first time when you leave the job like 15 days notice or whatever

let your company know that you re leaving the job as you got a new job

resign and start your new job which you prefer and like  

The best decision is to resign as you will not be able to do justice to you and the organisation.