Men prefer titanium eyeglasses frames, and the most popular titanium frame brand for men is definitely Flexon.
Titanium is an amazing material that is significantly lighter and stronger than other metals.
Also, titanium is hypo-allergenic, and quite flexible. These qualities make it ideal for use in eyeglass frames.
Titanium frames do have some drawbacks, however.
For example, it is impossible to adjust titanium, so manufacturers combine other alloys into the frames so they can be adjusted.
Also, titanium becomes brittle at cold temperatures, so they are not well suited for cold climates, or for leaving out in the cold as they could break more easily than other eyeglass frame materials.
Oakley makes some great titanium frames, and we prefer the semi-rimless styles. Calvin Klein has some nice titanium designs for men. But for value, we love the Columbia line of titaniums. The frames are very well made and are sold at a more reasonable price point.