They sometimes got a little too sappy for my taste, but I liked them overall. Yukiko's was pretty good throughout because the romance doesn't come out of nowhere (she's sending pretty obvious signals from like, rank 4). Chie doesn't have that, but at the same time, I like how she works up the courage to basically ask you out. I dunno what else to say... it was a cute relationship. I enjoyed dating Rise, but the lead into her romance route was flawed (but that should go without saying.)
Ai Ebihara's is just incredible, full stop. The most nuanced and well-realized romance route in the game, by far. It doesn't feel like an afterthought.
Ayane's is goddamn hilarious.