Maven very often has a feminine connotation, even though it “shouldn’t” and even though it is technically neutral. Maven is 1600 times more likely to be a girl’s name than a boy’s (per web name site) and that is not an accident: many, many people subjectively feel “maven” to be feminine. Yes, Maven comes from yiddish mavin, meaning “he knows”; and is basically a synonym for “expert” which is neutral. And perhaps promoting stereotypes, Maven can be fine as a neutral descriptor for expert in regard to arts, aesthetics and more educated professions. But Maven often connotes a female expert, and so be prepared to confuse or jar your audience (of course some prefer this!) if you insist on using it indiscriminately; for example “a football maven” would not bring to mind a male sports fan/expert, but a female who knows her stuff about the game. “Guru” is perhaps the opposite of Maven, in that it is more common to use of men, but is technically neutral and can be used of either.