I have a Bernina with the automatic tension that I really like. I've never used it for quilting though. It would be very hard to get an accurate 1/4" seam and all the thread adds a lot of bulk.
It's great for edging fabrics so they don't ravel as you sew them and can be used in place of a sewing machine for some things. I make all my pajama pants exclusively on a serger.