I have a Baby Lock Symphony that I really like. Several of my friends have the Melody and really like them. Other of my friends swear by their Janome's. I would suggest checking these two brands out thoroughly.
Have you taken the Kenmore's in to a really good sewing machine repair shop that is willing to tune up an older machine? The older Kenmores are good machines. I would never give up my 30 year old Kenmore. It sews a beautiful straight stitch and is all metal working parts. I took it in several years ago for a tune up and it came back sewing like new.