I use LAME 3.96.1 because it's the latest final release. I used Ogg Vorbis for quite some time but when I bought my little MP3 USB stick I switched back to MP3, which provides me with good enough quality (as long as I can't tell the difference to the original I call it good enough

). I'd only switch to a new codec if it provided the same quality as LAME at about half the file size.