I have the complete Kempf (stereo) and the Arrau sets, used to have Schnabel on vinyl (borrowed permanently by college friend), and have some Serkin and Rubinstein as well. I also have the recently released Ronald Brautigam SACD/Hybrid of
Sonatas , Op. 13 ("Pathétique"), Op. 14 Nos. 1 & 2, Op. 22. It's been released as volume 1, so I presume there will be more installments (hopefully). Brautigam plays the fortepiano, and I was really surprised at how beautiful and dynamic the instrument sounded. It really is a must have recording. The sound quality on both the stereo and sacd layers is excellent.
I also have some Pollini
late sonatas, which are played with his usual athleticism and are very interesting. Kempf tended to be more romantic and traditional, but he also maintained slower tempos especially in the Hammerklavier, which killed the wonderful rhythms. I read somewhere that Kempf had said something about Beethoven being deaf and therefore making a mistake with his tempo markings, which is the type of statement that cannot be supported.
Serkin although drier and more restrained, is probably the most moving for me. Arrau was muscular and romantic and as always elicited a wonderful tone from his instrument. Unfortunately, the Kempf and Arrau are only available in sets now and are expensive. The Pollini is more readily available in smaller selections as is much of Serkin, of which I recommend his
Expanded Edition. The recording has the three famous named sonatas: Moonlight, Pathetique and Appasionata along with a previously unpublished live performance of Les Adieux, which is more than worth the price of the recording!
I also have some John O'Conor. He is also very plummy, and tends to use the pedal a lot. I have his recording of the Waldstein and the sound of the recording itself is not of stellar quality, although the interpretation is of high quality. I haven't heard his late sonatas so I can't say anything about them, but the recording quality on the one I have didn't encourage me to buy more.
I also wasn't crazy about Earl Wild. Although his virtuousity cannot be faulted, I don't quite like his esthetics.
I wish I could say that one of these sets was definitive, but with Beethoven I need to pick and choose.
Edit:
Tyson,
You are probably aware that for keyboard instruments Bach's Well Tempered Klavier is called the Old Testament while Beethoven's Sonatas are called the New Testament. Personally, I can't understand how anyone couldn't just love them.