MP3 is more of a common standard and is supported by more stuff. Depending on what you use to rip mp3 will be of higher quality, and end up being better compression for less size taken up.
WMA pro is a new thing, and isn't supported by much of anything other than computer media players.
If I were you I'd google 'EAC setup guide', get the EAC program, and follow the guide to setup the LAME mp3 encoder. You can't get better quality than a LAME encoded mp3.