Welcome Ardell!
I have been using all cotton for both piecing and quilting ... but after a workshop with a local thread expert and seeing her samples, I'm expanding to include other threads ... I had always thought that the 'stronger' polyester would stress the cotton in the quilt.
But I wouldn't go with the cheapest, good quality thread will behave and perform better in your project. Some machines are a tad picky too, some threads end up being 'linty'.