You might want to join the homequiltingsystems group at groups.yahoo.com for additional comments. That is an active group of longarmers who have a wide range of systems.
The rule of thumb is to spend a year researching longarms before actually buying one, and to try out as many different brands as possible at quilt shows. It's a lot like purchasing a car in that what suits one person doesn't suit another. Also, there is a learning curve with longarms; some people purchase one and then are too intimidated to actually use it!
From what I have read and systems I have tried out at quilt shows over the years, my top-end choice would probably be Innova. Since I'm not sure I want a system that costly, I am thinking of getting a Voyager 17 with Hinterberg stretch frame in the short term.