There are lots of great machines available. I say focus on your "must have" features and the machines which provide them, then try out all those machines. (For me, the number one "must have" is dual feed dogs.) A great place to try/buy is a major quilt show, since they're all in one place at the same time. Then you can buy what you decide on from a local dealer. The last day of the quilt show is a also a good time to buy from a dealer there, since they will make great deals on the display/trial machine used at the show.
As to your intent to use the machine heavily, just make sure you clean and oil the bobbin area at the beginning of each sewing session and at each bobbin change while sewing. It's the best thing you can do for your machine to keep it running well.
Have fun shopping for your new machine! Take your time deciding. You need to make the best choice for your needs.