Molly, I use Lagarith since two years ago and, apart the fact that VLC doesn't like to play files encoded with it - while MPC has not problem - I'm quite happy with it; FFVHUFF should be almost the same, but, because I'm an old dinosaur, I stick with things that works until they don't work anymore... "if ain't broken, don't fix it!"
But I must admit I'm curious to test this new losslees coded, to see if it's faster and less CPU demanding than lagarith: http://magicyuv.com