Dear M:
I think you must listen again to Mrs. Uchida. Perhaps, you should wait some years to do so. Her version of Mozart is absolutely perfect because, among several other considerations, it sounds natural. Even if she is cold as the south pole (what I really don't believe), calculating everything - as you said - it doesn't matter at all. By the way, watch her playing live: you will probably change your mind, because she is deeply emotional in the stage.
In the other hand, the pianists listed above (especially Horowitz, Casadesus, Perahia and Pires) have interesting approaches to Mozart, and - as they sound so different - shall create to you a broad concept of the composer's interpretation.
If you can, listen also to Gould, Pollini, Marcelle Meyer, and Andras Schiff: another ways to play Mozart, and - in the case of Gould in particular - some very odd insights. Finally, it's very cool to listen to some version on the fortepiano, to compare the sonority and its impact on phrasing, pedalling and dynamics (Staier is a good choice).
Best wishes!