I think my favorite character that I've written is Claire in Broken & BMS. Thanks for mentioning her! She was the first really well-developed original character I created, and I enjoyed writing her. I liked her personality and the role she played in both stories.
I'm struggling with least favorite character because there's two ways to answer that - least favorite because they're not well-written or least favorite because they're not likable. Least favorite because they're not well-written would be most characters I wrote between 2000 and 2002 LOL. There's not one that stands out in my mind as being particularly awful; they were all just kind of one-dimensional. Least favorite for being unlikable... I guess Jamie in By My Side because he was a douche. He was based on a guy I went to college with, who I had a crush on before I found out he was dating my roommate, but when I saw what a roller-coaster ride he took her on, I realized I was better off not liking him. So I actually liked writing the character of Jamie because I could see how Claire could like him, but I could also see why Nick hated him. He's least favorite for coming between my power couple LOL.
These are some of my favorite characters in other people's stories:
Nick in Running Up That Hill - He is such a jackass, but I love the way Steph writes him. His narration always cracks me up, and his scenes are usually my favorite part of each chapter. He has a unique take on things compared to the other guys LOL.
Nick in Save a Prayer - This Nick is like the opposite of the other Steph's Nick LOL. Instead of acting like a douche, he actually becomes the hero and takes on the role usually reserved for Kevin, that of the leader. It was cool to see Nick step up and save the day! And dig bot flies out of Jordan's brain!'
Nick in Remember Me This Way - What can I say; most of the recent stories I've read have been Nick-centered! This is a great example of angsty Nick, and angsty Nick is one of my favorite Nicks there is! I felt so sorry for Nick in this story. It's hard to imagine what it would be like to slowly lose your mind, but Rose did an awesome job showing what it might be like through Nick's perspective.
Amanda in Something Beautiful - I wanted to hate Amanda in this story... first because she went along on a trip that I wanted to be just Nick and Brian... and second because of the sneakiness she was up to behind the scenes. But I couldn't hate her. I actually really liked her. She wasn't Mary Sue or Anti-Sue; she was just REAL. Far from perfect, but not annoyingly flawed. Just flawed in one major way that made for an interesting storyline.
Brian in Between the Lines - All of the guys in this story were actually really interesting because they were our Boys, but with a twist. But Brian was especially lovable. He was always upbeat, committed to his team, a good friend to everyone but especially Nick, and also a bit of a hoarder LOL. I really enjoyed him.
Kevin in The Importance of Fly Fishing - No one writes Kevin better than Mare. (Not that I read many Kevin stories by other authors LOL.) She does a great job at showing Kevin in his big brotherly role, but also letting his subtle sense of humor shine through. I really enjoyed him and his relationship with Nick in this one.
Ciara in Cover Me With Dreams - One reason I'm not a huge fan of full-out romance is that I have to really like both characters individually and as a couple to want to read a whole story about them, with no other subplots to keep me interested if I'm not so into them. Nick in this story is simply amazing, but Ciara is an equally good character. I though she was interesting on her own, and I adored the way her relationship with Nick grew and changed over the course of the story.
Kara in The Market - Another great female lead, this time not in a romantic role. Kara was just believable, down-to-earth, and cool, and I loved the part she played in Nick's life.