What would you do? Scale Up or Out on the VMs?

No, it's not the ABC show.

Would you rather have a few big VMs that are running similar to Windows SBS which has 2 or 3 roles per Windows Server VM?

Or

You would rather split the roles to per VM?

For example: DC will have its own VM, Exchange will have its own, File Server will have its own, Virtual Center will have its own without the other add-on, etc.

Just wondering on what's the best practice out there and what people do in their environment.

Scale Up or Out?

I personally do a scale out in our environment.

A lot of time and work during a windows update process but if the VM is down, it doesn't affect the other roles.