Do you sew? If so the serger is great for finishing edges so the fabric doesn't fray. If you don't sew but think you might one day, then if you can afford it, buy it.
As for brand. I have a Pfaff and have had no problems with it at all. A friend has a Bernina and likewise no problems. Baby Lock is also good, as is Viking.
If you get one get the 4 thread. You don't need the 8 thread styles.
yes, you can use them with quilting. I just don't.