What a coincidence I noticed this list while listening to Watching From A Distance. Before clicking on it, I immediately thought Patrick Walker should be in it. I have yet to hear another vocalist who has an even more emotional voice than that guy, damn. While I don't know some of these vocalists I definitely agree with the ones I do know, so good job.
Then it would be a top 13. Although these two easily beat John Haughm and Daniel Brennare in my opinion. Lastly, I might be wrong here, but doesn't Thomas Helm do the clean vocals in Empyrium? He does them in Noekk at least, but haven't listened to Empyrium in months so I could be wrong.