Mass Effect has two leads, Mark Meer and Jennifer Hale, but you’ll only hear one of them as Commander Shepard per playthrough. According to player stats, most people play as a guy, meaning Mark Meer is their Shepard throughout the trilogy.
However, Meer encourages players to give FemShep a go - purely so they can enjoy the performance of his co-star, Hale. Speaking with PC Gamer, Meer says that he’s a huge fan of her work, and doesn’t have any problem with players choosing to only play as FemShep because of her performance.
Last year, I did another trilogy playthrough as FemShep while I also happened to be playing Guild Wars 2 as a Sylvari woman. My double take when I realized was pretty funny. Jennifer Hale is supremely talented and she lends an air of gravitas without getting into comical over-acting. She just has a perfect voice for a badass!