I used to be using Audio Catalyst. Best settings are probably a matter of taste, I usually use variable bitrate and set it to a max bitrate of 192kbs.

However, I have been told numerous times that LAME would be much better in terms of sound quality than Xing's encoder, even though Xing is much faster.

I cannot hear a big difference with my simple ears, but I didn't really compare seriously yet.

Till