Hand Sewing Needle #17 by Osborne has a triangular point and a long eye for easy threading. Sailmakers use a triangular shaped needle to open a rather large hole in the fabric. This cuts down on chafe problems when a long length of twine is repeatedly pulled through.
Needle size increases as the number decreases. The #16 needle is good for most work, but as a general rule use larger needles for sewing through many layers of fabric and smaller needles for seam work. Simply use the needle that yields the smallest hole without undue trouble.