SSAS Impersonation Smackdown - Specific Windows Acct vs Service Account

Recently I was helping a client with their Analysis Services database structure. In this particular environment, there are a lot (and I mean A LOT) of AS db's. One of the first things I noticed is that almost every single one was using the service account to do the impersonation when processing, which is a very very bad idea. "But Chris, why is that bad idea? Don't we want to use dedicated service accounts for our SSAS stuff?" The short answer is yes, you do want dedicated service account for SSAS, just not that one. Below I'd like to highlight each of the different impersonation modes available and there use. And what's the difference between the data source screen with credentials and the impersonation anyways?