I used Mettler Silk Finish cotton thread for years in my machine for piecing. Once I tried Aurifil 50wt 2-ply, though, I never wanted to use the Mettler again. The Aurifil is very smooth, leaves almost no lint in my machine, and I can fit more on the bobbin (because it is finer than most threads). It has been plenty strong enough for machine piecing; probably would not work as well for hand piecing, though.
For hand piecing I prefer using a glace cotton thread (thread has been glazed to make it stronger, smoother, and unlikely to tangle). Glace cotton thread should not be used in a machine because it can gum up the tension.
I also like the Aurifil 50wt 2-ply a lot for quilting on my domestic machine. It isn't strong enough for frame quilting with my midarm (Voyager 17).
My favorite thread for quilting on my midarm is Glide thread, which is a trilobal polyester. I tried cotton threads first (King Tut, Signature) but had some shredding and breakage with them; never have those problems with Glide.
So far I prefer cotton thread for piecing -- especially Aurifil 50 wt 2-ply (gives me flatter, more accurate seams). I experimented for awhile with 60wt polyester in the bobbin, then with both top and bobbin, but find Aurifil top and bottom gives me better results.
The differences might seem slight to some people, but over the years I have come to appreciate the cumulative effect of slight improvements on my quilting results.