Perahia was not fortunate enough to have the best recorded sound at his disposal. His recordings, being very good, cannot compare to Uchida flying on the wings of Philips.
It matters, because Uchida's velvety tone was duly registered, as was her left hand, as were the strings' and wind's gorgeous colours of the ECO. Uchida's recordings have matured extremely well and can be listened to today, 25 years after the takes, without any need of remastering, contrary to Perahia's, where even the 24-bit work has been unable to lift up the sound much.
Perahia sounds forceful and even percussive, his left hand barely audible at times. Banging all the way, it's difficult to find a pianissimo in his accounts. I believe that, being a first-rate pianist, he simply was let down by the recording engineers. Sony hasn't been a first-rate recording outfit since the 50s,those glorious days of her predecessors, CBS and RCA.
Uchida's first editions are still on the used market at outrageous prices. Grab them, and enjoy the riveting Philips sound that does such a favour to Mozart's masterpieces.