IMHO -

PianoTeq gets 1st place, and TruePianos gets 2nd place (of the choices given). HOWEVER, I'm a keyboard player...

For non-keyboard players (i.e. having BIAB play MIDI or dragging in MIDI clips into a DAW and rendering) I would not be surprised if the opinion was that any VSTi would do.

If you are a keyboard player who has played acoustic and if you have a reference point about what an acoustic *should* sound like under difference circumstances (individual keys in/out of tune, new/old piano wire, hammer age/wear, etc.) then you will like the modeled VSTi's because they usually allow you to dial in these variables to taste (esp. PianoTeq).

Also, for players, how the VSTi's react to your use of the damper pedal makes a big difference.

To my ear, the PianoTeq and TruePianos VSTi's 'blossom' in response to the use of the damper pedal. I assume it is because they are calculating on the fly what waveform to be sent based on what notes are currently 'in play' and whether there is resonance from the other un-damped strings.

It is a sound different than room reverb, though. And apparently it is not something the 'rompler' VSTi's can reproduce on the fly because in their case, I assume the sound of the sample is 'baked into' the waveform, and the name of the game is to simply look up a sample to play at a given velocity.

To my ear, the modeled VSTi's have a more 'rolling' and 'evolving' effect, that changes based on how much the 'soundboard' in the VSTi is being driven when the damper pedal is down and allowing notes to sustain.

For the OP, I guess the best thing to do would be to demo as much as you can, in the context of the BIAB song you are mixing, and use your ear as the final judge.

Anyway, my two cents...

Chris