You've added to my list, Cole. Thanks very much. "Herzlich..." 727 was there, just beginning to explore it, but really taken with it in just a couple of play-throughs. "Schmücke dich..." 654 is a favorite already, and making some progress with it. Am adding your other two suggestions to my growing stack to try playing. I've learned enough from all the help on this thread to finally have my own current favorite, "O Mensch..." 622, partly because I'm close to playing it without complete embarrassment!
I'll see if I can find the performance you cite by Biggs. I think hearing performances that you and others who have the knowledge and experience will help me better and more quickly understand how I should approach some of these pieces -- until "It sounds good." to me, which is, I think, the ultimate goal.
By the way, I took a quick look at your website and found my all-time favorite old hymn, "A Mighty Fortress". I planned just to sample your playing, but enjoyed the entire performance very much. You have the right pace and "authority" to it, and I enjoyed all the variations!
If you have any references or starting suggestions on registration for any of these chorales, I'd be greatful -- just learning where to start on that remains a challenge for me.
Barry Gerken