For the orchestrated version, I agree that the Reiner/Chicago version is one of the best and the standard all others are compared to. For the piano version, I prefer the version by Byron Janis on Mercury. The recording is a little thin sounding but very listenable. This disc also has the orchestrated version by Dorati and the Minnesota Orchestra so you get both for one price. I have the Richter/Sofia version and I find the recording is almost unlistenable although the performance is fine. I also have the piano version by Evgeny Kissin. This is a much more modern sounding recording but a slightly different interpretation of the piece.
