Oh, you've fallen for Garrett, huh...? I can understand that. Geez, Sophie. You make choosing so hard, I love both plots. But I'm gonna go with the Garrett story. It sounds more interested and Novie just sounds like an awesome character. Really, I'll love either whole-heartedly, you're a brilliant writer, but I think you should do Untitled and give yourself an Alex/YaLC break, but then of course come back and do that too. ;) ... that made no sense.
I'm for "Untitled" - I think that the sister dynamic would be a really interesting thing to explore and read about, and if it's done realistically, it'll add more depth to the story rather than just a usual romance. And I'm interested to see how Garrett comes in the picture, and why he, of all people, would be the first person to believe in her. If she's always been overshadowed, I'm curious as to how and why Garrett is the one to truly value her. I don't know...while "Know It All" sounds like a fun read, I think "Untitled" will be more intriguing.
I love Garrett. But I also love Young & Lost Club and because Alex is a semi-sequel…? Honestly, I'll read anything you write. But I really love Garrett. So that's my useless contribution.