Flac is the way to go. If I had it to do over I would use flac. At this point 600+ cds I am in no hurry to reconvert... I just picked the top MP3 rates long ago when I did not have the HD space for it.
If you got the HD space use Flac for backup. Then keep a down converted mp3(320vbr+jointaudio)/AAC/OGG set for everything else.