As the title suggests, this is a very important question. Listed below are the pros and cons of such decisions
1. You need to travel outside the US
2. You work for a large company, get a level 4 salary, and have documents to prove Specialized Knowledge and Control
3. Your project with which the Labor Condition Application is filed may be ending soon, and you need the documents to prove your case
4. Extension with same employer
5. It eases the employees’ minds
Not to Premium
1. New petition
3. Working for a small consulting company
4. All your friends are upgrading to Premium
In other words, if your case is easily approvable, do Premium.
However, in new cases, or cases requiring additional scrutiny by the Citizenship and Immigration Service, I would advise not to premium, especially if Premium processing has just started for your category. What can happen is that a lot of folks will file in Premium and officers will be inundated with work. You may supply all evidence to prove your case, but you risk the chance of a denial. For busy officers it is better to deny a real case, then approve a false case.
Once the case is denied, it is useless to appeal, because under the trump administration, the AAO is rubber stamping all of Citizenship and Immigration Service’s decision. You can fight in federal court, but that does cost money and time.