Synthogy Ivory II - Italian Grand Expansion -- They sound very, very well.
Otherwise the Galaxy 2 series which is composed of three pianos. 1. German Baby Grand, it's a Bluthner. 2. Boesendorfer 290. 3. Steinway D
Personally I love the Vintage Steinway D also from the Galaxy series.
Very particular, but for recordings with harmonies that are not too loaded with notes, there is also the Imperfect Samples - Fazioli library which sounds very good; the harmonics and the sum of the sounds are excellent. The beatings can be heard very well, but as I repeat to you, it is a very particular library, the sound is truly imperfect, that's why I like it so much. One is used to always listening to these sounds recorded in the best studios with the best equipment; this library is effectively imperfect but very characteristic. Imperfect Samples also makes available a 127-level library, practically you have all the timbres with 127 dynamics. Also from Imperfect Samples there is the piano suite which includes a Braunschweig upright piano (8 GB of samples), a 13 GB Hohner grand piano, and the Fazioli, the 16-level version at 13 GB. Then there is the Yamaha C3 Alicia Keys library, but it is not very suitable for classical music; it is more for pop music, in fact, the library does not have very progressive sounds, few dynamics, which is something that is very necessary for classical and less for pop. Excellent libraries are those from East West which, instead of using the Kontakt player, use the proprietary Play player. The latest East West library is truly wonderful, perfect in everything: timbres, dynamics, and there is something for all instruments, but they send the complete library via Hard Disk; it weighs one terabyte and costs quite a few dollarsโI don't remember the exact figure, so don't take my word as gospel, but it seems to me we should be around 3000 dollars.
Another truly beautiful and affordable library is the Garritan Steinway, which is the only official Steinway library. Steinway has made its best Steinway D available to Garritan, perfectly tuned and recorded in the best recording hall. It's like listening to a real Steinway!
The ArtVista that Gennaro recommended to you also sounds very good, but in my opinion, it is more of a Jazz sound than a classical one and, anyway, in terms of quality, it doesn't hold a comparison with those already mentioned: we are talking about the quantity of recorded samples. The Fazioli, just to give you an example, has 8000 sound samples and weighs 13 GB; ArtVista's Virtual Piano weighs barely 500 MB compared to, however, the 6.5 GB of Galaxy II Steinway etc. etc.
My ranking (in terms of personal taste) is this:
1. Garritan Steinway
2. East West Gold Pianos
3. Ivory - Italian Grand
4. Galaxy Vintage D
5. Galaxy II Steinway
6. Galaxy II German Baby Grand (Bluthner)
7. Galaxy II Boesendorfer 290
8. Imperfect Samples Fazioli
9. Alicia Keys for POP, not for classical.
Have fun.