What would you advise or recommend as a backup strategy for customers using SQL Server hosted in the cloud (Azure VM's or AWS EC2). We have SQL Server Enterprise deployed in an AAG configuration. Currently we have weekly full backups on a Friday evening which are stored on a volume on a different server (domain controller - don't ask!). It does take a long time and doesn't seem to be an efficient way of backing up. Also, the primary SQL server is currently the active server for performing the backups, but would prefer this to be passed on to the secondary server - however, for some reason this was failing as it didn't support the backup method and required 'copy only' backups - but don't fully understand this. The server also performs transaction log backups every 15 minutes.
Can you suggest anything else we can and should consider including the use of snapshots to ensure application consistency and ensure we can recover from failure without any data loss (or at least no more than 15 minutes).