Glasses that are comfortable to wear should fit you exactly. On one hand, you should get eyeglasses with right prescription, neither too strong nor too weak. Stronger prescription glasses will make you feel dizzy. And you often get headaches with the stronger prescription glasses. If the prescription is too weak, you can't see things clearly and often get blurry vision and eye strain. Only the right prescription eyeglasses can make you feel comfortable to wear. On the other hand, the glasses frame size should fit you properly, neither too tight nor too loose.
To get a pair of comfortable glasses, you shall pay attention to the glasses frames and lenses. The eyeglasses frames must the right sizes that fit for your face and head. And the materials for glasses frames must be good to touch. And glasses frames with nose pad are recommended. Again, to get comfortable vision, you'd better buy glasses lenses with your current prescription so as to get proper prescription lenses for your eyeglasses frames.