Vier letzte Lieder
This is probably the more idiosyncratic of the major recordings of the Vier letzte Lieder out there. Schwarzkopf and Szell seems to be the standard recording, but I am not all that enamored with Schwarzkopf's sound. She is a little too brittle-sounding. She was also on the way out, vocally speaking, when she got around to doing this with Szell. His conducting is top-drawer. If you're into Szell and Strauss, this recording is a must. I am not all that taken with Szell (though he was quite an excellent Wagnerian), so the recording is a solid second or third, depending on how I rate Norman.
Speaking of, Jessye Norman's disc with Masur and the Leipzig forces is generally the "best" out there. Norman has the massive sound thing going for her, though Masur takes it all far too slow. Not that Von Karajan drives through the score (he is kind of drag-y, too), but the tempi for the Norman recording are oddly slow. Perhaps Jessye needed the room to be as expansive as she is, but the orchestral work is just weird. Now, it could be as weird and terrible as it wants (and it's not that bad), and her vocal work would still save the day. She sounds superhuman in this recording; it's hard to describe how big her voice is here. This might be the perfect recording if you like Norman or care about the soprano voice.
This one, with Von Karajan and Gundula Janowitz, is probably as close to ideal as this score can be. Her tone is called silvery, bright, and inhuman (less flatteringly, of course). She has a brighter reading than Norman's huge sound, and that might not go well with some people. However, I think that she blends in well with the Straussian soundscape. There is more cohesion here, speaking from an ensemble-interested point of view, than in the Schwarzkopf or Norman recordings. Yes, she is a bit impersonal, but I have never thought Strauss to be the most personal composer. He is always distant, even here, in his last songs.
I think I had an earlier post about this, but I use 1975 as a sort of line in Von Karajan's career. Up to '75, he was a great a conductor (in his repertoire) as there was. After then, he became indulgent and obsessed with a smooth, bright orchestral sound. This Vier letzte Lieder was cut in 1974. There were orchestral details I hadn't noticed before that Von Karajan brought out in this piece. Luckily, it was recorded in the Jesus-Christus-Kirche and not the unacceptably boomy Philharmonie. There is a clarity of tone and orchestral precision here that is wonderful, to say the least.
If you want three Vier letzte Lieder recordings, buy Schwarzkopf/Szell, Norman/Masur, and Janowitz/Von Karajan. They each have their benefits. However, if you want only one, get the Janowitz disc. It strikes the best balances between orchestra and soprano. Janowitz has the most Straussian soprano for this piece. Von Karajan is still a great conductor in 1974. In other words, this is the best of all worlds.