I’d advise using Stretch. It’s more recent and we aim to have best compatibility with the most recent version of Raspbian, although we try to make things backwards compatible where possible.
It shouldn’t really matter whether you use Stretch or Stretch Lite. There’s a trade-off between the (greater) time taken to burn a full Stretch SD card versus more time taken to install stuff that’s missing on Stretch Lite as part of the install process. So, if you prefer having the desktop environment, then that’s what you should go for!
As far as the scratchy audio, @gadgetoid will be able to give a much better answer about that than I could. :-)