From what I hear about embroidery machines, people love their Brothers.
And yes, get the largest possible workspace you can for quilting or embroidery. Machines can be expensive, but I spend more time behind my sewing machine than I do my car these days and you do lose money by continually trading up.
For a used machine, you might see if you can get a Bernina 830 with some sort of service plan. I've been using an 820 given to me by a friend (same model no embroidery unit) and like a lot of things about it. Unfortunately, it does need to go to the shop for I think a thread that I can't find... anyway, the 820/830 models were not super popular with the public and is easy to find negative reviews of them. As a working machine, I was very happy with mine. Huge throat space, well lit, auto thread, auto bunch a things and bells and whistles. The one thing I wasn't so happy with is especially for an embroidery machine I would want the ability to buy prewound bobbins. The Bernina bobbin is expensive and proprietary, it isn't a 15, L, M or whatever. Bobbin winding is fast and easy and the bobbin is large but in a my world, I rather like just popping in a prewound.