I would recommend trying a number of brands (and combinations of machine/frame if there are options for a machine) before deciding.
Machine weight is just one factor. The friction between the machine and the rails is even more important for reduced physical effort, ease of movement and smooth curves. A lightweight machine with high friction is going to be more fatiguing than a heavy one with little friction. There are large machines out there that you really can move with a light touch of the fingers.