Hi Diana,
I bought a bolt of Northcott's solid white (colour 010) and I LOVE it! It is a higher thread count, but still nice and solid, and the threads seem to have a very consistent thickness. I definitely recommend it for piecing or for applique.
I also have bought a lot of Art Gallery's solid fabrics (and the prints too
). Art Gallery fabric is beautiful, also a high thread count, but softer and finer. I would not use it for an applique background, but I have been doing some detailed paper piecing with it, and it is wonderful for that. It also holds its colour very well in the wash.
In the dreadful section, I would not recommend any of the Free Spirit solids -- they are coarser than Kona, and also fade more than I would like in the wash.
Happy quilting!