I have Bernina machines and they seem to like Mettler cotton silk finished thread. It is expensive and the last time I purchased any I found a place online. You can do a search and sometimes find a decent price. JoAnn's also sells Gutterman sometimes at 50% off and it is a fairly good thread. Haven't tried Connecting Threads brand but that may be my next stop as even thread prices are going up.
mltquilt