I have a sit-down Sweet Sixteen from HQ that I love, but I did notice that HQ recently came out with actuators that can raise and lower the machine. So if you want to sit while quilting you can and if you want to stand the next time you quilt you can. This would be a must have for me. I don't think I could stand all the time. I think there are other brands that have the lifts on their frames as well. I almost went with another less expensive brand, but I am very glad for the support, education HQ provides and how well it's made.
I can use any size needle from 12 - 20 without having to re-time the machine and I've been able to tension any thread that I've desired to use. Make sure to ask that... I almost went with the Sunshine, but they said I could only use 16-18 size needle and I wouldn't be happy if they timed it 14-16. Well sometimes I want to use very fine thread like silk and sometimes I want to use a heavier thread like King Tut, so I need the needle versatility.