I'm assuming you mean computer-wise...
The Xilisoft line is decent, with a whole gambit of options that you can change/optimize to your liking. However, if you have a DRM'd *.wma or Apple iStore purchased *.M4A...you can forget about it. Not bad for the $39.99 USD. I've been using it for the past 4 years...not a single failed convert. Although if you try to upconvert too much or set the quantizer of the audio to low it will fail due to a gambit of reasons; but it's worth it. If you want the full flexability to convert FLAC audio to normal (.wma/.mp3/.mp4/.m4a) you'll need to go with their Audio maker suit...but it in itself has a few extras. Worth checking out.
http://www.xilisoft.com/audio-software.html