I have always used Isacord for my Bernina machines and like it. I have also used some Robison-Anton and I have a large set that I bought from a dealer on Ebay. I do use polyester thread vs rayon because when I first started doing embroidery I was doing it on things for the GKs and needed it to be colorfast. Check with your dealer about what they recommend and try it out.
mltquilt