I want to migrate Google Drive from a 'Google Apps for Business' account to a personal Google Drive account, as my company has decided to move to office365+sharepoint, and close down the Google Apps for Business account.
You can use Backupify's free Snapshot for Google Apps tool to accomplish this.
Snapshot for Google Apps extracts all the Gmail & Gchat messages, Google Drive documents, Google Calendar events, Google Contacts entries and Google Sites data from a single Google Apps user account.
You can then import that data into another Google (or Google Apps) account.
You'll have to add the app as a Google Apps administrator.