I use whatever I have or can get, mostly donated thread. For years, the only thing available was Coats & Clarke and it worked just fine.
My first quilt made with cotton/poly fabric solids back in the 70's was made with 100% cotton thread that I found someplace. I made a massive 100" square quilt, and tied the quilt 12" apart (using an old 100% polyester blanket for the batting).
Guess what? The moment I finished the quilt, the seams started popping. I never did get the quilt to stay together. It has had broken seams for 40+ years now. I wish I had used cotton/poly on it. I'll never fix it because it is the only quilt my grandma and I worked on together. She and I tied it and I really don't want to tear all of that apart to fix it.
I'm now using Aurifil and loving it, and still using up the stash of Coats and Clarke I have from 3 generations of sewers. Just use it and make up your own mind on when to use it. All the rest is opinion.