I have all three of Schwarzkopf's recordings , 1953, live 1956 and 1965, with, respectively, Ackermann, Karajan and Szell. I also have Popp/Tennstedt and Janowitz/Karajan.
I have to say, that, though I enjoy all these recordings, it is the Schwarzkopf/Szell recording I like best, as, for me, they get right to the heart of these songs as no others do. With Strauss's gorgeous writing for the soprano voice, it is all too easy to forget that these are Lieder, and to ignore the texts and just revel in the sheerly beautiful sounds, provided by a Te Kanawa, a Fleming, or indeed a Janowitz. I also feel the more mature Schwarzkopf better suited to the songs than the young one. After all, these are Autumnal songs, and the voice of youth doesn't seem quite right somehow. Certain phrases in Swhwarzkopf's later recording are now so firmly etched into my memory, that they spoil me for all others and Schwarzkopf and Szell seem to be completely at one in their vision. Two places stick out for me, Schwarzkopf's voicing of the words langsam tut er die mudgewordenen Augen zu in September, where Szell matches her tone perfectly in the orchestra. The other is in the final song, Im Abendrot. The way Schwarzkopf sings the words so tief im Abendrot has an almost cathartic release, not matched in any of her other recordings (nor by any other soprano), and superbly seconded by the rich carpet of sound Szell provides for her. Ist dies etwa der Tod, asks Schwarzkopf/Eichendorff, and as the orchestra creeps in with the quote from Tod und Verklaerung, one can only assume that it is. For me it is one of the classic discs of all time, and would definitely be one for my desert island.