A matter of perception
CP is for those who feel that their jobs were safe till CP was done. The reason for this is the fact, that once u r in the home country waiting for the interview and u lose your job, u r stuck right there. Chances of appeal are remote. In the case of AOS, u have an EAD and the denial chances are remote.
I opted for CP first, but had to resort to AOS due to the layoff
Dilip (GCAR)