My kids had a microscope and I did my own test. I looked at all the brand of thread I had. I was shocked at the flubs that all brand name threads have but some a lot more, looked liked barbed wire.
I like Aurifil for piecing. It's doesn't break on me. That's odd that it does for others. Aurifil comes in every color you can think of. It's up to the seller to have those colors to sell.
I buy Aurifil online, the price at the shops are way over priced in my opinion on all thread. I never buy thread at a quilt shop. I stock up on the colors I like when I find a sale. I like Superior thread and most of the other quality brands too. I use Connecting Threads poly a lot, it's thin and strong. I recently tried MSQC brand of thread. I was pleased with it.