I have a Janome 6600 and LOVE it! It does everything I ask it to. 9" that,which can easily quilt a full sized quilt with fmq. I've read many people manage a King sized, but I haven't tried. I love the accufeed and the built in walking foot. It's also pretty darned quiet.
I've recently started sewing bags, with lots of interfacing and fusible fleece lining, and this machine takes it all. I'm constantly amazed at what it will sew through.
I'd love a Sweet 16, sit down, but that's just not an option for now, either. I keep squirreling away money, but at this rate it will be another 5 years before I've saved enough for that .