I have always owned Pfaffs, and the reason is their dual feed. When Pfaff went bankrupt and Viking bought them, that ended their patent. Several other brands now have this feature. I'd take cotton samples with 6-8 crossing seams (star center) and denim with a crotch seam (yeah, I know you may never sew pants) and give each machine a try. And take two long strips of cotton and see if the ends match up after sewing without pinning. The dual feed foot should not be visible to the stitcher and be easy to "pop" into place in the back of the foot.
Sandy Quilts