There is one best thread for the job. NOT TRUE.
My machine only runs with "such-n-such" thread. PROBABLY NOT TRUE. Or, hopefully not true. You probably are not comfortable adjusting the tension as you change threads if this is your opinion.
I have seen so much verbage to this effect lately on the blogs and facebook. It forced the interest in my looking back over many of the quilts I have done, both for myself as well as for clients to see what threads I used most freuently, and why each was chosen. That is probably the more important point. I don't choose threads for a quilt because I like stitching with a particular kind of thread. I choose it because it is what the particular quilt would look best with.
There is a nearly endless selection of threads that each quilt can be quilted with. I will admit right off to not liking to quilt with cotton thread, and more than a year ago I just sold off all my cottons. It is not that my machine can't run with it; I just don't care for the additional lint or the more frequent thread breaks. So, with that said, just within the realm of polyester thread, there are a whole host of options. There is also metallics (also a poly thread) and silk. So, lets look at some of the quilts and talk about why I chose what I chose.
This is Sea Glass. You have all seen it, I know. It is batiks and hand-dyes, and the background is pieced in a watercolor style. Right up front I'll admit that this quilt may have looked great quilted in the shinier threads (Glide, Rainbows, Magnifico - as examples), at the time it was made, I didn't use of know of Glide and Magnifico wasn't around. I chose, instead, a very fine 100wt Invisifil. It is so thin that it really only leaves the texture behind, which is exactly how I wanted the quilting to be. All of the colors and textures of the fabric are visible, and not overshadowed by the thread. In retrospect, though the sheen of Glide would have been pretty, I do think that the 40wt thickness of this thread would have overpowered the delicate texture I was aiming for. JMHO.
I also used a blue Rainbows thread on the waves and the inner blue border as well. It's a 40wt variegated thread, similar to Glide, but for me it is occasionally prone to unpredictable shredding so I use it in small areas and rarely on entire quilts. It works well here. Glide would have too, but it's not variegated.
This is a still-unfinished whole-cloth quilt on silk Radiance. Today, I would quilt it using silk 100, but 20 months ago I chose the Invisifil, another very fine thread. It stitched beautifully. The actual quilting thread is barely noticeable, just as it would be with silk. It leaves behind beautiful texture. This is really not the style quilt you'd want to see a 40wt Glide all over. It would be too thready for sure. The very fine thread allows the fabric and texture to steal the show.
Postcards from Venice was my first intentional show quilt. Admittedly, two years I was not adventurous in my thread choices, nor did I have much selection beyond So Fine. It is completely appropriate for the quilt though. I used a metallic thread, which I pretty much loathe stitching with on areas where the fabric has a metallic flecking, but everywhere else, I wanted a flat look without sheen. This is a quilt of an inlaid mosaic floor. Shiny didn't seem right. Was this the right choice? I guess.
In my uncertainty, I used a metallic bobbin thread on the back of the quilt though to help hide where I had backtracked over some seams more than I may have wanted. This got good reviews from all the judges - not that it is required, but that it was an interesting and unexpected element. It is nice to have surprises.
I do love Glide, as many of you all do too. I have used a gold Glide on a couple of recent show quilts, including the one below. This quilt is made with the Stonehenge fabrics, and several have gold flecking. I think the shiny gold thread looks nice on them, showing up just the right amount. I particularly like the use of a slightly more showy threads in this case because the fabrics read as mostly solid or mottled. On true prints, however, Glide is not always my preference.
I guess it's about time to wrap up this thread discussion. This is a recent quilt of mine, Big Bertha. I will be at MQX in 2 weeks. I stitched this with silk 100 in 4 different colors, each matching the fabric. It's monochromatic so that the texture shows, not the thread color. I chose the finer silk thread over a So Fine or Glide because I stitched several areas quite densely, I don't care for the look of thread build up. Silk thread is pricey -- probably $40 on this quilt on the top only (not counting the bobbins), but it runs so smoothly, not having the shredding that poly can have.