I've been working more with Logic Pro X lately and generally like the sounds and synths that come with it. But I've been looking for the killer grand piano sound and I may have found it in the form of Best Service's Galaxy Vintage D virtual grand piano. It operates within Kotact Player and sounds pretty sweet. I've yet to tweak it much—I'm not entirely thrilled with the middle octaves as I find them a little too ready to "twank" when hit hard, but I think I can make some adjustments to tone it down.
If you wish to hear a sample, check out Galaxy Vintage D Test in the Bits and Pieces section of the Music page.