Hello,
Today I made the trip to a reputable piano dealer and played (plus a few others) Roland LX6, Kawai CA701, Yamaha P525, and a house brand piano featuring TP400/W. (All of them through my own pair of Sennheiser HD560S; the speaker sound of all these models, even the expensive ones, is so disappointing…)
In particular while playing the Kawai, I had surprising thoughts along the line of: "If I buy this, I can perfectly do without my VSTi piano -- these built-in Kawai samples are so nice!".
Then, after coming home late in the evening I thought Let me fire up my VSTi piano now that the memories of the store visit are still fresh.
And boy oh boy -- it is a different world altogether. No way the built-in samples (even those nice Kawai ones) could replace this.
My favorite is VI Labs Modern U, as recommended also by @David Lai above. Its sound is rich, real, has body, has breathing space, makes actual music. I literally was back home -- physically and at my favorite piano.
As for Pianoteq, it is not my cup of tea. The nice thing about it, as others will undoubtedly have already mentioned, is that it is free, and super easy, to demo/test it yourself and form your own impressions and opinion about it.
Discussion/opinion wise, sampling vs. modeling is a never ending rabbit hole, as this thread also demonstrates with already about 30 posts in mere hours.
The (expensive) Roland I played today (which also uses a modeled sound engine) didn't sound half bad at first ear, but soon it was "yeah, modeled, not music to my ears".
I strongly believe that Modern U and Modern D are the best VSTi pianos around today.
Cheers and happy exploring,
HZ
@Nik