192 is generally considered the rate at which very few people can detect an mp3 from the same song as a WAV file.
Many people can't tell the difference even at 160 or 128.
You may have golden ears or think you have golden ears. In that case, use 320.
Or use 320 if you know you will never have space problems. 320 bit-rate files take up nearly twice as much space as 192.
I use 192 whenever possible. If my original source is monaural, I use 96, which contains as much data as 192 stereo.