I like a lot of different ones -- it really just depends on the quilt's design. I love thread painting! So much fun! But I guess if I had to pick just one, it would be feathers. I love seeing how they transform when used in different ways -- wreaths, in corners, as an all-over design, feathered hearts -- the different shapes available, being able to add in little flourishes & curly-cues & paisleys ... there just seem to be so many options!