I always come back to the Grand Upright at the end of the day. I just think it has the best feeling / sense of sitting in front of a real upright piano, without it being too defined by its character.
Otherwise I'm using one of my top 3 grands: Silver / White / Royal 3D.
I've used the Amber a lot, and while it can be very pretty sounding, it's more of a filtered / special use case sound that I don't have the room for all the time on my Piano 4. I feel like it also has less of the illusion of sitting in front of a real piano than the Grand Upright.
The Pearl is nice as well, but maybe a little too rich sounding. So I usually use the White Grand when I'm after that rich sound.