Another vote for the Viking Megaquilter. I've been taking FMQ classes on our Megaquilter and it's awesome -- all the features you need and none that you don't. It loves Aurifil thread, and it also loves being cleaned and oiled frequently.
The Megaquilter 9", the Pfaff Grandquilter, and the Janome 1600P are all the same machine and are all made by Janome -- excellent build quality, very heavy duty, high-speed near-industrial machines.