WAV files are about ten times larger than an MP3 of the same recording. CAF is what Apple's audio tools and iOS apps use. WAV is at home in recording, editing and mastering; CAF is the usual choice for audio inside Apple's apps and development tools.
The defaults suit most files. Under Options you can trim the start and end.
This pair uses the compatibility engine, ffmpeg built for the browser, because CAF cannot be written by the browser's built-in codecs. It is a one-off download of about 10 MB that the browser keeps, it is slower than the built-in codecs, and it takes files up to 1 GB.