I think you need to be more descriptive about the type of sound you are looking for. Without getting too technical, you can break down the sound of a piano into three parts: attack, sustain, and decay.
Attack is the sound a piano initially makes when the hammer strikes the string. Some people like a hard percussive attack, and some like a milder attack.
Sustain is the sound directly after the attack where the note maintains the same loudness for a while. The length of sustain varies from instrument to instrument, as well as the overall tone. Some like a bright sound. Some like a deeper sound with more overtones.
The decay is the natural lessening of the tone after the sustaindue to, among other things, the vibrations of the strings becoming smaller. The decay is in many ways an extension of the sustain, but the gradiation of the decay varies from instrument to instrument.
I hope that helps you analyze the type of sound you are looking for. Pianos tend to vary a lot, even between the same model or the same brand, so you will need to play a lot of different instruments.
You should probably go around to a few dealers with a notebook, play a lot of instruments, note what you like or don't like. It seems like a long process, but pianos are expensive, and anyone should take their time in deciding which one they like and would buy.
Good luck.