Have you tried out all of these machines yourself? It's a lot like buying a car; what is the best fit for one person may be very uncomfortable for another.
Here is another thread about machines I ran across here:
http://www.quiltingboard.com/t-18099-1.htm
You may want to do searches on these specific models to see what other comments may have been posted about them on this forum.
I don't think it's a good idea to invest in a longarm until you have done a year's worth of research to determine which one would be right for your situation. If you are a new quilter, definitely do not buy a longarm until you have some experience under your belt.