I recently got a Voyager. So far it likes King Tut and Signature threads just fine. I tried Connecting Threads Essential Pro polyester thread, but it is just slightly too weak for my machine and breaks occasionally (it is a 70wt poly, so very fine). The previous owner of my machine said that Aurifil 50wt 2-ply (which I *love* for piecing!) breaks in my machine, but Aurifil 40wt works fine.
A lot of longarmers like King Tut on top and Bottom Line poly in the bobbin, so I will try that combo next. The Bottom Line is a 60wt poly and probably just enough stronger than the Essential Pro to work for me. An advantage of using poly in the bobbin is that the bobbin will hold more thread, so you don't have to stop to change the bobbin as often. Also, the thread disappears more into the fabric so is less obvious. If Bottom Line works in the bobbin, I will try it as the top thread also as I often like a very unobtrusive thread for my quilting. A third advantage of using poly in the bobbin is that it creates less lint to clean out.
The best prices I have found online for King Tut, Signature and Bottom Line threads is this website:
http://www.machinequiltingconnection...=index&cPath=2