My faves, with a pretty wide range. There are very few recordings that I've not liked (and now can't even think of any). When I'm not satisfied, it's not usually the singer, but the conductor's phrasing and tempi, e.g., too fast.
Janowitz / Karajan (my intro to the piece)
Fleming / Thielemann
Popp / Tennstedt
Norman / Masur
Isokoski / Janowski
Schwarzkopf / Szell
--Bruce