I kinda have a feeling that there weren't any male alicorns because...they haven't ascended yet. Shining Armor is the most likely candidate to be the first. He's got enough magical oomph, but I think the catalytic event may center around Cadence...and maybe their foals.
Cadenece and Shining seem to have a yin-and-yang complementary dynamic.
Although...maybe before he ascends, he needs a "batshit insane" period...kinda like what Twilight had.
Well, in my opinion there aren't and there probably won't be any male alicorns because that would make them look kind of girly; plus, they only make pretty alicorn princesses just to sell them (Hasbro...)