It depends on how much you want to spend. Any of the major brands are good. I love my Bernina 440 but it was about $3000. It works really well on most quilting projects. The only trouble I've had is sewing through a welt on blue jeans. The dense fabric pulled the needle out of the needle holder. When I sew things like that I switch to my Singer treadle. It only does a forward straight stitch but can handle some really funky fabrics.
If you have the money I'd buy a modern machine (if it is for most quilting jobs)from a good local dealer with a good warranty. Most offer classes and maintainance. There good older machines but I wouldn't have the experience to know what is a good deal on them. I would also worry about something going wrong with it after I buy it. If you can get an older machine from a reprutable sewing machine store that will warranty it or offer repairs/returns you could see if you like one. Good Luck.