WAV files are about ten times larger than an MP3 of the same recording. AIFF is uncompressed and native to Mac audio software. WAV is at home in recording, editing and mastering; AIFF is the usual choice for audio production on the Mac.
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 AIFF 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.