Blahel is absolutely right, there are as many opinions as there are machines. And everyone of them is valid. I don't like Bernina, I am a Janome fan. My best quilt buddy had one, top of the line, and after sewing on my little basic Janome changed brands. And there are as many people that do the opposite, so it's all a matter of taste and what you want to do.
I do just straight piecing, with maybe some decorative stitching. I have an older Janome that can do some fancy stitches and buttonholes, but I don't need a machine that can calculate the square root of pi to the 100th position. Try to figure out what you will use the machine for the most, and start there. Then try and decide if you would be able to even figure out the more expensive models. Some of them have a fairly steep learning curve. Do you really want to HAVE to take a separete class just to learn how to make your machine do one of it's functions? Then go to different dealers and ask for a demo and to be allowed to play with the machines for a while. Any reputable dealer will be happy to show you everything they've got and let you try the various machines. Then go home and sleep on it before plunking down your cash. Unless you have a more experienced quilter to go with you and guide you.
Good luck and let us know what you got!