I'm pretty sure you may have already realized it, but Japanese women really like cute things (cf. Aggretsuko, Love Live!/[email protected]
, KyoAni), so they will inherently lean towards the girls more than the boys, most of the time.
However, I'm pretty certain that said Japanese women do not like the girls 100% of the time, so they lean towards the boys instead.
Additionally and completely outside of vtubers is the fact that there is a wide sex wage gap in Japan, so it is also unlikely for Japanese women to donate for either
of these two kinds of vtubers. Hence, they go for the fujo (i.e. being an yaoi/yuri doujin artist) or cosplayer route in order to get some side money while they stay at home being a housewife, or so.
I may also add the writer route too as it is quite obvious that Japanese women themselves, 99% of the time, are going to be the ones writing your favorite otome game.