The best nipple for the Evenflo glass bottle is the Evenflo Ultra. It is definitely the nipple that most closely resembles the breast. Unfortunately Evenflo quit making them due to low sales. I got some on E-bay.
The best, shortest, chunkiest nipple to get right now is the Evenflo Comfi.
Dr.Browns Preemie nipple has the slowest flow but is really long and narrow but most babies learn to take any shape nipple pretty fast.