My suggestion is to try different machines at a quilt show if you can. After you decide on your brand of machine, I would buy the biggest machine and frame that I could afford and had room for. All of my friends that bought small machines have upgraded to a bigger machine. The higher price of the machine is the "whistles and bells" you add on.
I have a Gammill with stitch regulator (LOVE LOVE LOVE that). Not computerized. I see other machine brands that I might like, but I don't know any brand that can beat the Gammill frame!!!