Physically: Men. Yes women give childbirth but as a whole men can lift heavier amounts of weight, can take more damage, are better suited for protecting, and in my opinion they look better than women (some of them anyway).
Mentally: Men. Men go by logics and facts. Women go by their emotions. Men are logical when dealing with relationships and life. Women go by their fantasies and things they want to believe rather than what's there. A man can kill and crush a woman easily; a woman can't even hit a man!
Men's and women's bodies are structured very differently. Men tend to be someone taller than women, and their bodies have higher fat and muscle contents. Because of these basic physiological differences, it is impossible for all men and women to have equal strength. Although, with proper training, it is possible for some women to surpass men who do not have any strength training.
Biologically, men and women are built differently. As a result, they do not have equal strength. Noting that they do not have equal strength, or the same strengths, does not mean that each gender does not have advantages over the other. For example, as a general rule, men tend to be physically stronger than men. However, researchers report that women are stronger in the sense that they generally are capable of sustaining higher levels of pain that their male counterparts.
Men and women's bodies are created differently and have different kinds of strength. Really it depends on what your idea of strength is. Women can endure days worth of pain during childbirth, while men's bodies create hormones that allow their muscles to get bigger than a woman's would. If strength means bigger muscles, then men are stronger. If strength means the ability to endure, then women are stronger.