>>530869630
Both.
At first it was just her design that caught my eye when I first tried season 1 out back when it aired, but since she didn't have much screentime (didn't watch the OVA) there wasn't much of an impression before I moved on.
It was actually Ai-chan's design that drew me back to this franchise a couple years on, but once I actually started reading the game stories it quickly became clear who my favorite was.