And the best Piano plugin is (drummroll):
A matter of taste
There are many many libraries out there which sound fantastic once you find out how to use them properly. Others might not suite your playing or your genre, no matter what you do. IMO The best overall allrounder for production music is Alicia’s Keys, but there are people who don’t like it. On the other hand: The one that I never liked is Emotional Piano, but it seems to be quite popular among folks.