Daibhidh
If you're wanting it for playing classical piano. Pianoteq all the way.

They're the only one officially licensed by Steinway & Sons.

Garritan used to be, but Steinway pulled out.
I suspect because their software protection got cracked.

Thanks for the tip, that's the main thing I'm looking for ... and the ability to configure it for expressive play on different midi keyboards. 

emeraldsoul
What type of music do you intend to make with it? Are you solo jazz or classical, or is it in a rock or pop mix?

I mainly looking for expressive standard piano play in itself, but jazz/blues/classical is the genres closes to heart.

Checked out Addictive Keys ... massive project just to get it installed ... definitely not addicted. 

PianoTeq would be my suggestion.
 
I own the stage version and will eventually upgrade to the standard (which allows the positioning of multiple mics).
 
Before I got the PianoTeq I used the various NI pianos and also the XLN piano.  But the PianoTeq is SO much more responsive that I never bother with any other piano.

iRelevant

Fleer
Essentially, you've got three choices. TruePianos, Pianoteq and the one from Arturia
I'd opt for Pianoteq all the way. Incredibly detailed, wonderfully playable and choices galore.
You'll have to pick a bundle first. I got the Electric plus Hohner. Then added the Steinway and Blüthner.
Love the Blüthner most of all. Sweet and subdued. Mighty fine.
But you can start with Steinway bundle too, if you prefer.
Anyway, best to buy Standard instead of Stage.
But you can upgrade whenever you want.

I'm leaning most towards Pianoteq of all those ... thinking of starting with the Stage and the Steinway bundle. I'm very satisfied so far with the playability I get with this. Is there any major reason to go for the Standard edition ? I see I will be missing Piano model tweaking ... but to me this sounds more like minor stuff as long as I like the sound I have. Arturia is off the list, minimum requirement is XP compatibility and 32-bit functionality. Truepianos have it, but has an really annoying AI way of presuming what I wan't, where as Pianoteq installer is a dream ... you get to select and configure everything as you want. 
 
What would you say is the main thing I'm missing out on by not going for the Standard edition now ? 
 
Thank you very much for your feedback, by the way :)

You’re quite welcome.
The mic positions, as Michael wrote, are quite interesting. And the FXP presets: “Pianoteq Stage will load only the settings that are available in the Pianoteq Stage interface. If you want to enjoy the many creative presets in the FXP corner, you need the Standard or Pro version” (Pianoteq FAQ).
People develop their own presets for specific kinds of music, often in the Pro version, but you can load them all in Standard.

I would defer to the piano experts here but I have a question. Doesn't the 4 GB RAM of 32Bit restrict some sampled instruments? Are any of the ones being talked about modeled? Modeled wouldn't be a problem. If you weren't going to be doing any recording you should be OK but in a project there could easily not be enough room for sampled instruments with all the layers and velocities and articulations sampled.  

Michael A.D.
PianoTeq would be my suggestion.
 
I own the stage version and will eventually upgrade to the standard (which allows the positioning of multiple mics).
 
Before I got the PianoTeq I used the various NI pianos and also the XLN piano.  But the PianoTeq is SO much more responsive that I never bother with any other piano.

Thanks for the feedback. I share your impressions. There is nothing that comes close to PianoTeq in terms of responsiveness and expressibility when playing, TruePianos is also good but not as good in terms of adaptability to the nature of the keybed you are using as well as personal style of plaing. It's like a new world opening up here. I also like TruePianos, but I already have the cakewalk edition ... and can't defend forking out 120 € (-30% discount) for the standalone ed. XLN piano, although apparently made by sweet brother on the other side of the mountain (Norway vs Sweden ) have the worst installer I've seen in a while. It's in league with NI (and for that matter the CCC) ... but where talking a simple piano plug-in here ... not a major DAW host. 
 
I think I will start out with the Stage version ... and the Steinberg Package. Take it from there. Moneys's always tight, and then I will have the future option of adding packages as possible. I hope the Standard package only contains further options in terms of character of sound, and that there are no limitation in customization of expressiveness/playability. I'm a little nervous about what the "Preset (fxp) loading" limitation in Stage ed compared to Standard ed is about. Hopefully nothing of major importance.

B-dad in da know. Three modeled options, thus: TruePianos, Pianoteq and Arturia.

Fleer

iRelevant

Fleer
Essentially, you've got three choices. TruePianos, Pianoteq and the one from Arturia
I'd opt for Pianoteq all the way. Incredibly detailed, wonderfully playable and choices galore.
You'll have to pick a bundle first. I got the Electric plus Hohner. Then added the Steinway and Blüthner.
Love the Blüthner most of all. Sweet and subdued. Mighty fine.
But you can start with Steinway bundle too, if you prefer.
Anyway, best to buy Standard instead of Stage.
But you can upgrade whenever you want.

I'm leaning most towards Pianoteq of all those ... thinking of starting with the Stage and the Steinway bundle. I'm very satisfied so far with the playability I get with this. Is there any major reason to go for the Standard edition ? I see I will be missing Piano model tweaking ... but to me this sounds more like minor stuff as long as I like the sound I have. Arturia is off the list, minimum requirement is XP compatibility and 32-bit functionality. Truepianos have it, but has an really annoying AI way of presuming what I wan't, where as Pianoteq installer is a dream ... you get to select and configure everything as you want. 
 
What would you say is the main thing I'm missing out on by not going for the Standard edition now ? 
 
Thank you very much for your feedback, by the way :)

You’re quite welcome.
The mic positions, as Michael wrote, are quite interesting. And the FXP presets: “Pianoteq Stage will load only the settings that are available in the Pianoteq Stage interface. If you want to enjoy the many creative presets in the FXP corner, you need the Standard or Pro version” (Pianoteq FAQ).
People develop their own presets for specific kinds of music, often in the Pro version, but you can load them all in Standard.

OK. I see. To me these features are at the moment minor, I guess the desire will creep in with time. At the moment I'm just trilled with the new found expressibility in my existing keyboard (A-500 Pro) and could possibly starve to death while playing :) It's like going from a 8-bit sound card to 16-bit for the first time. Almost unbelievable.
Thank you once more for your input, I will now be able to order with confidence.

Anytime you want, you can upgrade to Standard at the same price (difference). Once in a while Pianoteq even offers sales, so you may get lucky and upgrade to Standard when those sales kick in.
Don't forget to demo the Blüthner. She's quite something.
Also check the forum (http://www.forum-pianoteq.com)