The type of needles you use are really important. I use different types of needles for different steps in the quilting process. For piecing your patchwork together I suggest Schmetz Sharp/Microtex Needles. For machine quilting or free motion quilting I will switch over to these Schmetz Machine Embroidery Needles. These machine embroidery needles have been heat tempered to prevent bowing and bending while machine quilting at high speeds, giving you better tension and a better stitch.
The 90/14 needle works perfectly with a 40wt quilting thread.