I love thread as much a fabric. I have tried them all. Some are great some not so great in each of my machines. I buy a spool of any thread I haven't used before and try it out. My go to thread is Aurifil, Superior, and Wonderfil for piecing. All 50 wt or higher. I do not use Coats and Clark thread. It's short staple cotton ends twisted together. It causes me all kinds of problems from slubs to shredding to tension.
For quilting I like Glide and Superior specialty threads.