Great topic Danny.
My favorite unedited factory style is ModernJazzBallad from the CVP-509 (also on CVP-609) and played on my Tyros4.
The style, from the Swing/Jazz genre, is very simple (3 parts) with only Drums (Live!Drums-Brush-Kit), Bass (Mega-Voice Acoustic Bass), and Jazz Guitar(Mega-Voice Jazz guitar).
Each Variation has been programmed over 8-bars and variations C and D are in double time, and the whole style sounds incredibly real with terrific bass lines and guitar strums. I used it to play Somewhere Over The Rainbow which I uploaded here some time ago.
I also agree with DannyUK about the Play4Sofa style being a masterpiece...I have also used it as basis for many other styles.
Ian