Fuuka has her own fans, including me, but yes, compared to other P3 characters Fuuka fans are in the minority. And from what I've seen, Fuuka fans don't participate in waifu wars that much. It's like Spongebob hamburger meme, we like Fuuka, and that's it.
Also, I really love her official artwork from P4U, I mean just look at her. Literally it's one of three things I like about P4U. (The others are Mitsuru's design and Labrys' backstory.)
She's irritating in combat without the cool designs or depth of character the others have
I personally dislike Fuuka because she has very little presence in the story. Usually the other characters are more engaged and have an effect in the outcome of events.
Yukari voices her opinion constantly. Mitsuru is the leader and also hot. Aigis is very involved in the story and becomes a central character when she joins. Metis I'm also meh on, but at least she's really strong in combat.
probably no phenotypes that stand out that people like, yukari, mitursu and aigis can be described as sexy characters. fuuka not so much. more cute than sexy.