Pianoteq 6 wins over Ivory 2 any day in my opinion.
I own both, bought both years ago, 10 years ago maybe? I ran with Ivory for a while but could not escape its two dimensional quality, albeit a well-sampled two dimensions. I stopped using Ivory when Pearl came out.
I've also demoed every version of Pianoteq, without excitement. Until version 6 . This most recent version is amazing. Petrov especially. So playable.
Plus with pianoteq they have other cool instruments that use the platform.
Pianos are an extremely subjective category. You can easily demo pianoteq, wheras you can't demo any sample library. Those you buy with your fingers crossed!