I’ve tried most sampled and emulated pianos on the market with a focus on live playing: whilst load times and dongles don’t mean so much in a studio environment, they are a crucial factor in selecting a live instrument (for me).
I’ve worked with Pianoteq pretty much since it was first released, and I’ve developed a kind of hate-love-relationship with it: I love the expressiveness, but I’ve never been happy with how it sounds especially in the area around middle C - just misses the texture, brilliance and “bite” you can get out of the real thing and some good sample libraries (although I also find a number of sample libraries lacking in this area).
I don’t like to use dongles live (too easy to lose or break), so even though I like Ivory (American Grand is really nice) and use it frequently in recordings, I haven’t included it into my live setup. BTW: if you want some more options: my other two favorite recording piano libraries are Garritan CFX and the Galaxy Vintage D - great stuff!
Presently, my favorite piano for live is the Addictive Keys Studio Grand: it has a very reasonable memory footprint, doesn’t require a dongle, installs on three machines in parallel (studio, live & backup) and has a nice universal sound and texture. I’ve created a custom preset which is pretty generic, using only one set of virtual microphones, with a pretty balanced sound. Then I use some EQ, compression, chorus, reverb and delay plugins in my main piano rack to customize the sound - currently using about 10 piano presets.
I do use Pianoteq in my stage setup: mainly for its electric piano sounds (Rhodes, Wurlitzer, CP-80). I like the expressiveness I get from it, and it is less quirky to customize than LoungeLizard. I use dedicated effects plugins after it instead of the included ones - I get a better sound and higher flexibility by using dedicated phaser, flanger, chorus, compressor and amp plugins in my ePiano rack than using the ones included in Pianoteq. To me, the secret to a good rock epiano sound is the selection and the tuning of the amp plugin after the piano ;-).
So, give the Addictive Keys a try - definitely worth it!