BladeEnc Quality  
The Fraunhofer encoding-routines (used in L3ENC, MP3 Compressor and MP3 Producer) are widely known for creating the best soundquality, but this is not always true.
The Fraunhofer Institute is mostly interested in increasing the quality of low bitrate MP3:s since they hope this will allow for realtime radio transmissions over internet, which they hope to make a lot of money from in the future. Nothing wrong with that, but unfortunately it gives some unwanted side-effects:
  1. Since their routines are so heavily geared towards producing low-bitrate MP3s, they really cut the music to the bones from frequencies that are harder to hear in order to boost the presence of easily heard frequencies. This works well if you encode for low bitrates, but when you encode for higher bitrates it only gives the result that you fill up some frequency bands with more information than is needed, while other still are almost empty. The routines used by bladeEnc fills up the frequency bands more equally, therefore producing better quality when encoding for higher bitrates (and worse quality when encoding for lower bitrates). If you ask me, I consider the limit where bladeEnc passes L3Enc in quality to be 160 kBit.
  2. Their sophisticated routines for cutting away waveforms that aren't so important sometimes backfire and makes the music sound a bit like if it is played under water. This never happens with an encoder that is based on the ISO-routines (like bladeEnc and mpegEnc).
So, my simple conclusion is that Fraunhofer's routines produces a better quality when dealing with low bitrate MP3s (128 kBit or less) while bladeEnc is to be preferred when dealing with high bitrate MP3s (160 kBit or above).

When comparing BladeEnc with other encoders based on the same ISO routines (mpegEnc for example), you should know that my main focus always has been quality. I have made some optimizations, but NEVER sacrificed quality for speed. So, unless the creator of some other ISO-based encoder has added some tricks of his own to increase the quality (very unlikely), BladeEnc should surpass (or at least be on par with) all the other ISO-based encoders.

If you want some more in depth quality comparisons I can really recommend UsE! - The User Oriented MP3 Encoding Guide. Just remember that there is no technical test that is 100% accurate. The final judge should always be your own ears (as long as you have a good soundcard and a decent pair of speakers).