Most of my sewing is clothing. I use Metrosene exclusively for that. It performs well with my vintage Bernina 830. I have had trouble with other brands being too linty or spooling incorrectly. I dutifully bought expensive 100" cotton thread for piecing and it drove me crazy with the curling. So I sheepishly went back to Metrosene for my last quilt.
I felt more comfortable using it with my first FMQ quilt because of familiarity. It took one variable out of the mix. I knew how it should perform.
I will say the I bought Connecting Threads brand of cotton thread, and it may win me over, I just haven't had time to use it much.