Wow you will probably get as many suggestions as there are machines! When you say best machine for quilting do you mean for piecing or for FMQ?
I have a Bernina and I love it, but it does not meet the criteria of being reasonably priced. However, I do not regret for one second the investment I made with this machine. I didn't get one that has embroidery capability. If I had it to do over I would get the Bernina that has a stitch regulator for FMQ.