What's more preferable: CPA, CPC and CPM?

I am taking advantage of many campaigns and I am really in favor of the CPM model. I think it is the best. I also know that CPM offers amazing benefits and is the ultimate or branding campaign. In this, there is no need to think of the time spent for the ads to get clicked. However, the ads are displayed out here. On the other side, the CPA is also chosen by many advertisers as there is no need to determine exactly the pay for a download or sale; whilst, CPC is the most effective advertising campaign that is charged less.