For machine piecing, I generally use Aurifil 50 wt top and bottom. For machine quilting, I like Fil-tec's Glide top and bottom, but also use thread from Metro Embroidery and embroidery thread from our local LQS (but I'm drawing a blank on the brand name!). When I was hand quilting, I generally used YLI, and for hand piecing, I used plain ol' Coats & Clark.