Hello, what type and size needle do you use for piecing and for Machine quilting?

I'm way less than a purist - machine work or handwork I use whichever needle is handy.

depends on the thread size

it depends on what thread i am using-since you have to match the thread size/type with the needle size/type.

i use an embroidery needle with embroidery threads,
a metallic needle with metallics
a top stitch needle with heavier threads
a sharp for piecing- in the size that goes with the thread being used.
ect.

I don't know the size thread but it's essentiel from Connecting threads

Your size should be on the thread. I did go back to Connecting threads on the cotton it is 50 and on the polyester is 70.

I use 80/20, but the majority of what I do is piecing. If I ever have to actually quilt, I used an embroidery needle but the same thread. Worked find.