Call me old fashioned but I love the good old knee control for speed. Too bad they do not make these anymore. I guess when the companies got away from putting machines into the cabinets whenthey sold them , that is when they dropped the knee speed control. And by the way I also miss buying the cabinet with the machine.
New options are :more in the feet , Free motion, 1/4 inch, walkingfoot, open toe applique, piping, cording, you just can not have enough feet.
A cabinet ( so the machine base is recessed) with a really nice big surface area around it would be a great. I would accept less options on a machine to get a great base cabinet. I would forgo a needle up or down for a great cabinet( but most machines have this as a standard unless a really inexpensive machine) . The surface area you have is so important. After that the biggest opening for rolling up quilts to do the quilting.