I never thought I'd ever use some of the functions of the machine I bought, but as my skills grew so did my usage of more of the machine's functions. I bought my first sewing/embroidering combo machine used on Ebay and it is a great machine. It was two years before I tried out the embroidery arm. Now, I do machine embroidery as much as I do quilting. I wouldn't hesitate to buy a used one from your dealer. Not everyone has the positive experience I had with Ebay. Plus, if you buy from a dealer, they will help you learn how to use your machine and will be happy to service it for you. Sometimes people just trade in their old machines because they want to upgrade, not that there is something wrong with the machine.
Last year my husband got me a new machine. It was so complicated that I traded it in and ended up with a Babylock. The Babylocks and the Brothers are cousins and both are very user friendly. The problem I had is that the newer machines is that they try to combine sewing/embroidery/quilting functions with computer functions. Frankly, the screens that come with these machines are too small for me to easily manipulate (resize, change stitch order, edit) an embroidery design. So don't be seduced by the "big" screens that "do everything" and you "don't need a computer" or anything else. If you really get into machine embroidery, eventually you'll want to get your own software for your home computer where you can easily make changes. They even have machine embroidery quilting designs that will do the quilting for you.
Decide what your budget is before you go shopping and stick with it. Don't even look at machines that are too expensive for you. Some dealers will not tell you the price of the machine until you decide to buy it! So tell them upfront how much you have to spend and to not show you any machines that are out of your budget.
For quilting, I'd get the biggest throat possible. For ME, I'd get the machine that has the biggest hoops...at least a 5x7. And don't forget to check for what feet come with the machine. Most come with a 1/4" foot, but if not, you'll want to buy one.
If you are happy with the machine you have now, if you buy one in the same brand the feet you already have will probably work with the new machine. That can save a lot of money.