My first LP set of Fidelio was Karajan's, mainly because I'd seen Helga Dernesch perform the role of Leonore with Scottish Opera, and wanted a memento of her performance. I had always loved this set; however, when I came to replace LP with CD, I bowed to popular opinion, and purchased the Klemperer recording.
I am in a minority, I know (and I know this could well be because the Karajan was the one I'd got to know the opera with), but I was a mite disappointed with Klemperer, and a couple of years ago I replaced it with the Karajan. Returning to this performance after many years, it was exactly as I remembered; thrillingly dramatic, wonderfully played by the orchestra, and marvellously sung by a superb cast (all, mercifully, delivering their own dialogue). Many have said that they can hear the strain the role of Leonore puts on Dernesch, but I believe that they are being wise after the event (Dernesch, you will remember, retired from the opera stage for a while, after suffering a vocal crisis, and re-emerged a dramatic mezzo). To my ears, she sounds absolutely radiant, the climax to Abscheulicher!, shiningly and glowingly achieved. From her first entrance in the Act I canon, which is as a ray of light in the gloom of the prison, she is the very epitome of the faithful Leonore. I prefer her even to Ludwig on the Klemperer. Vickers is, if anything, even finer for Karajan than he was for Klemperer. Keleman's snarling bass-baritone seems to me just right for the evil Pizzaro (superbly matched by Karajan's blaring brass in his aria), and Ridderbusch makes a fatherly, kindly Rocco. With Jose Van Dam as Ferrando and Helen Donath as Marzelline (like Schwarzkopf, who sang the role for Furtwangler, an Eva of note), the cast could hardly be bettered. Karajan's tempi in the more dramatic moments of the score are usually that bit faster than Klemperer's (the moment when Leonore reveals herself is urgently thrilling), but he has plenty of repose in the more lyrical and reflective moments too.
Fidelio is a great opera, and there is no doubt the Klemperer is a great recording, but my personal preference is for Karajan, which works for me on a slightly more visceral level.