I have been using kimono silk only bc that is what was originally suggested to me. I have heard that Bottom Line, from Superior threads, is a good choice. They are a good company to work with, in my opinion. Here is a chart from their website that has thread suggestions for different applications:
https://vw-superiorthreads.storage.g...tion-guide.pdf (or go to
www.superiorthreads.com, scroll to bottom under education, reference.
You might also want to google flat back stitch. I've seen demonstrations of this method where even thread that was a completely different color did not show at all.