First of all, what's your budget?
My advice would be to go with either a Brother or Janome.
You are more likely to have certified service/repair providers within a reasonable distance. Just look for the biggest maximum hoop size available that fits your budget.
I have a Janome 350e that I love. This is an embroidery only machine. I chose this because I had a sewing machine that I love and I didn't want a multi purpose machine. It has two hoops - 5x7 and 4x6 and it's pretty easy to use. And it also has a USB port so that you can transfer designs onto the machine.
The Brother machines are also good, tough workhorses too, (I also tried 2 Brother embroidery machines at work: Brother Pe800 and Pe535 mentioned here) but as far as being more user friendly, having a better screen and more onboard editing capabilities, for the money Janome wins hands down.