As the majority of the population is heterosexual, opposite-gender transformation would seem to open up the most dating opportunities.
I hope you aren't straight!
can I transform at will...?
You have no control. It always happens, all the time. Whoever you are closest to, you are that gender. Always. Period.
Where should this comment appear?
This pairing only
Whenever "Transform into the same gender as the nearest person to ..." appears
Whenever "Transform into the opposite gender of the nearest person to ..." appears