Adding more random options:
wheatie mentioned Morisaki and I do agree that she'd be kewl :3 I keep thinking that she's older (because she's been there for ages) but she is actually 16 and thus perfect age
She's also genuinely a H!P fan (like Kanyon) and would probably be totally loyal and awesome. She's quirky and cute so yeah! I think she might end up being a supporting member though, I don't see her becoming popular enough to be one of the leads D:
Just came to my mind checking the pics forum, there's also Irori
Somehow totally forgot about her even if a few years back she used to be the one that ppl said would be a star. She's in Shugo Chara Egg, she's pretty amusing and seems to be good at girlbonding (lol), I remember when Takechan joined she was like immediately toying with her haha. She's 13 too, which seems to be an alright age to join Momusu. They've kept her look quite raw and innocent too, so there's room to really bloom and grow to be a beauty imo
I really kind of wish that Konatsu could get in even if she's 18 because she could really fill in for Eri when it comes to dancing, plus she has a really bold personality. Borderline annoying maybe (lol) but funny
She'd be risky though because even as an Egg she's not one of the most popular ones, I mean her pics almost never get scanned and it's like she doesn't exist etc. But I like her look and stuff. She is also kind of Kei-like because I've noticed other Eggs making fun of her in her presence, and she plays along with it really well lol
To be honest, I could write a speech for almost any Egg on why they are good candidates, excluding the more recent additions because I haven't seen any concert or backstage footage of them :/ I really hope that there'll be another DVD release at the September Egg concert, but not counting on it. But yeah I'm possibly way too biased to be discussing this topic
Cuz to me almost all are great in their own way