For US comics, check out El Goonish Shive - www.egscomics.com
It's a long runner (15+ years!), kind of slow paced (an arc about a night at the card shop took a year), and is otherwise really good. Gender shifting is played both for fanservice and for drama, and the weird overcompensating the writer did for LIKING gender shifting in his post-high-school years has been worked into the plot well enough.
It's not porn, but there's a lot of porny fanfic out there, and the artist has a Patreon where he serves up soft-ecchi levels of pinups.