WAV files are about ten times larger than an MP3 of the same recording. WMA plays in old Windows software and some older portable players. WAV is at home in recording, editing and mastering; WMA is the usual choice for legacy Windows music libraries. WMA 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 WMA 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. WMA is written at 128 kbps unless you choose another bitrate.