I think I would go for a Bernina, built in upper feed, stitch regulator, firm build,... I would keep my old straight stitcher along side it. I use it for all kind of stuff, from reupholstering bike seats, sometimes stitching through plastic, cardboard, and odd material. It's a fine machine, but it feels different than the more advanced computerised models. What ever model you end up buying, test it with top stitch thread and special threads you use, not all models are as flexible as we expect them to be. Make sure what you spend your money on is an actual improvement for the type of sewing you do, not just a new machine.