Which is the best thread to use for machine embroidery.....rayon or polyester? Also, what is your favorite brand?

I used Isacord.

I also use Isacord. However, polyester thread will hold up better after multiple washings.

They have different uses. Rayon has a nice sheen, but isn't colorfast. So, if the items will be used often and bleached(think kids) poly is a better choice.

I like poly due to it's durablility and my machine likes it better too :D:D:D