Some encoder facts
Hey, I wanted to post something about this soon anyway.
First off there really is no "best" encoder, per se. Encoders use "perceptual" methods to literally throw away audio information in order to save space at the price of some quality loss. They work by using some tricks using knowledge about how we hear. For example if two sounds happen at the same time and one is much louder, then we don't really perceive the softer sound much. Most encoders use this fact and just drop the information about the softer sound to save space. Bass isn't very directional to our ears, so low frequency stereo information can be folded down to mono without much noticeable degradation. Our ears are more sensitive to certain frequencies, and this is used to the advantage of encoders a lot.
Since they work on how we "perceive" sound, there's no way to quantify it. It's a subjective thing. In my own listening tests I found that one encoder may shine on a particular song and another does better on a different tune. Really, one may sound better on one part of a song and another better on a different part of the same song. Fraunhofer seems to shine at bitrates below 128kbps; LAME tends sounds best to me at bitrates above 128 and with VBR encoding (most of my critical listening tests with encoders was done about 3 or 4 years ago, so improvments may have changed things since then). Blade sounds pretty awful to me unless you use very high bit-rates, so I'd avoid that one.
All that said, I'm pretty darn fond of LAME overall. If you're using a Windows platform, just go to the encoders section at:
http://www.mp3-tech.org/ -- they have a no-brainer install for LAME and a front-end for LAME called RazorLame. I haven't tried WinLame, but I'm sure it's a fine front end as well.