It Makes You a Better Person
I have to admit that it sounds rather cliché, but being a male feminist makes you a better human being.
Let me explain.
There is a sort of spectrum among "men who accept feminism." It can perhaps be described in the simple phrase of "think globally, act locally." There are men who only think globally and do not act locally and those who do both.
Of the globally thinking: there are those who accept the political beliefs and policy positions behind feminism, such as pro-choice policies, equal wages, and other legislative remedies. That is perhaps what one might call the "least" feminism side of the spectrum.
Of those doing both: there are persons who have accepted feminism as a sort of lifestyle to guide their own personal actions, hence the "local." And for them, feminism is a way to become a better human being. Once you accept that feminism is an ideology or a way of looking at the world that is applicable to your own life, you cannot but accept that is an ideology of self-improvement.
Being a male feminist of that sort is like being a recovering alcoholic. If you read the descriptions of an "awakening" moment of a recovering alcoholic, you read how they realize that their very own lifestyle, from where they live, where they work, with whom they are friends, is based around their disease: alcoholic. So too, is the male feminist not truly a feminist, but a recovering chauvinist.
Our society is one built around chauvinism and misogyny, and it is the feminist who acts locally that realizes that their life too, is but a microcosm of that same system. And thus, the feminist realizes this, and begins acting, like the alcoholic, to slowly change even the tiniest parts of the world they inhabit into something better. By making things better, by fighting a system that denies humanity to others, they improve themselves, and they bring themselves closer to the humanity that society denies them as well.