I use machine embroidery thread for quilting on many projects. There is a little sheen to the thread which I like and it seldom breaks. It can be used in the bobbin if you like the colors to match.

I prefer cotton but I have used polyester sometimes. The appearance is very different so it depends on what you desire in that respect. I frequently use cotton on the top and bottom line (poly) in the bobbin. I have had good success with this combination.

I longarm quilt so about 99% of the time I use polyester thread. Cotton breaks often due to the high speed machine

Poly is easier to use for fmq but super has high quality king tut cotton that doesn't shred compared to other brands imho if you like cotton use superior

I use a variety of threads for quilting. They all seem to work well for me.

I use both on the LA, but prefer poly because so much less lint, doesn't break as often and I like some of the shinier threads on some quilts. Superior threads are my fav, but I also like Marathon trilobal that is same weight as BottomLine. One feature that I use to make thread choice is the weight--most cotton ones are #30 or #40 and I prefer a #50 or higher as I like dense quilting.

If I have thread breakage with cotton quilting thread I switch needle size from 14 to a 16 and it stops. I quilt on either a Babylock Jane or a Juki TL98QE.

"I wonder why Leah had the problem with cotton thread breaking."

Domestic machines are a little more fussy than longarms I believe.
I mainly use Isacord thanks to Leah!

I've FMQ with Connecting Threads Essential threads before, which are 100% cotton and didn't have a problem, but it's been several years, since I discovered Metro machine embroidery thread to FMQ.

My Jukie seemes to prefer cotton machine quilting thread. If not used it will break frequently.
ently.