I'm going to say that while it's a bit subjective whether the Kawai or the Bechstein is the finer grand piano*, my feeling is that the Kawai is the better executed Pianoteq model. As a later addition to the fold, it seems to have benefitted more from recent refinements, leading to a well-rounded sound and really extensive tonal control.
That said if you like the general sound profile of the Bechstein**, I'd recommend looking at two further alternatives: The Steingraeber, which I personally got as the "Bechstein but Better" entry in my collection and am extremely happy with. It has that same germanic percussive blockiness as the Bechstein but sounds far more organic to me. It also happens to be an amazingly adaptable and morphable one.
The other one worth looking at is Kremsegg 2, which features a beautiful Bechstein from 1899. It sounds amazingly modern but has a bit more character compared to the main Bechstein pack, as it was modelled from a specific specimen. It gives you realness without sacrificing the clean sound you may be enjoying.
* disclaimer: I'm a Kawai stan
** this kind of makes sense from your other choices: the Bechstein is more distinct from the Steinways than the Kawai