I like Connecting Threads cotton for piecing, and have gotten to like their new Essential Pro poly cones for quilting, especially now that it comes in so many colors. I have several different makes and models of machines, and don't have a problem using these threads in any of them.

I'm a big Bottom Line fan
It's a 60wt poly bobbin thread. My old Bernina will take it top and bottom. Sews like a dream, lies flatter than any other thread.
My Jems won't take it as a top thread. With them I use Aurifil 50wt cotton on top, BL in bobbin. Aurifil seams lie flatter than any other cotton 50wt.
http://www.superiorthreads.com

I use different threads for different quilts. C&C for many, Gutterman for special quilts

When I first started quilting, I used Coats and Clark because it's so readily available and recognizable name. After reading so much on here about thread quality, I've purchased Guttermans when on sale at Joanns and I do like it better. I also purchased King Tut once and love, love, love it! I'm anxious to try more brands and see how they compare. All it takes is time and money...lol.

I have started using Aurilfil and love it - it is less linty, feels smooth - and a big spool seems to last almost forever - not quite, but certainly long enough to make it more cost effective for me . Also that is the thread that my sister carries in her shop - and which she uses also.

Aurifil for the DSMs and King Tut for Miss Mitzie(Tin Lizzie). I have tried several brands, including Mettler, Guterman, Connecting Threads Essential pro, etc. My preference is still Aurafil and King Tut.

I use anything that isn't that really cheap,easy to break, fuzzy thread. I like Mettler, Superior, Gutterman, Signature...I forgot Aurifil (Which I'm mostly using lately).

Aurifil!!!!!!!!!!!Low lint, no breakage.

Well, last night on my way home I ran to JoAnn's (closest to me) and grabbed some more of the Gütermann thread. Let me tell you, my machine was SO much happier last night. The Coats & Clark that I had in there, I threw out. I am definatley going to have to find the Aurifil or King Tut brands and try them!!! Thank you all so much!!! :) Great to know what a lot of people use. :)

I prefer Aurifil and also use Mettler.