WAV files are about ten times larger than an MP3 of the same recording. MP2 is the audio format broadcast and DVD-authoring tools expect. WAV is at home in recording, editing and mastering; MP2 is the usual choice for broadcast radio and television audio. MP2 is lossy, so keep the WAV original if you may need full quality later.
The defaults suit most files. Under Options you can choose the bitrate and trim the start and end.
This pair uses the compatibility engine, ffmpeg built for the browser, because MP2 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. MP2 is written at 192 kbps unless you choose another bitrate.