What audio file format supported by OFP is the most efficient?

BAS team member DeadMeatXM2 recently posted the following analysis on BIS' OFP forums:

• Don't use OGG when you don't have to. The game engine takes a long time to decompress and process OGG
  files and their sound can get clipped, warped or sometimes not heard at all.
   
• WAV files provide reliable results but have a greater file size.
   
• WSS files are the best. They provide clear sound that rarely warps, along with a reasonable file size footprint.