I agree that test driving a lot of machines at various shows is a great way to start your research. I did that and discovered I don't particularly like driving the machine over the fabric - I prefer moving the fabric under the needle. This turns out to be a good thing as there is no way we could fit a frame in our house, and my back won't handle long periods of standing. So I am another happy owner of the HQ Sweet Sixteen (sit down).
Cheers, K