I use Isacord and Floriani. I like them both. The Floriani seems to be a little brighter and I am replacing most of the Isacord with Floriani as I run out of a color.
There are so many to choose from- the dealer I buy from stocks these- I am familiar with them and like them.
It's true that some machines seem to like some thread better than others. I agree that your should try different brands and decide what you and your machine like.
Enjoy the embroidery.