Tough question. There were so many great GCN games. Exclusives only?
• Metroid Prime
• The Legend of Zelda: Twilight Princess
• The Legend of Zelda: The Wind Waker
• Chibi Robo
• Mario Kart Double Dash
• Eternal Darkness
• Rogue Squadron II
Or multi-platform, because then the question gets even more difficult:
• Killer 7
• Resident Evil 0
• REmake
• Tales of Symphonia
• Harvest Moon: A Wonderful Life
I like her, she's "Cute". Not sure if you know but Shinji Mikami hated her, it was the rest of his team that wanted a female character like her, a little more passive/innocent. I have a feeling we'll be seeing more of her soon, so maybe she'll develop into a more confident, less green character. Jill is my favorite female character of all time, but I still really like Rebecca.
I really liked her in the game. There wasn't much character development, but you can tell she grew up a little as the game went by. From the first, when she meets Billy in the train and she's timid, until the very end, when she is more comfortable taking charge.
RE:0 is one of my more favorite RE games. I mean, really, the first 4 games are fabulous (that's 0-3). I love the story they tell.