lol I don't really like BoA either...but I do like her upbeat heavier dance stuff...HURRICANE VENUS had some very nice songs for me.
I would pretty much recommend those that have already been recommended. Although...I think I know your tastes a little bit better than some...you probably should stay away from any artists possibly connected with YUI lol
ICONIQ, Emi Hinouchi, JASMINE...they have some gems. ICONIQ more dancy ones, JASMINE and emi are super R&B, emi mixes in pop though a little.
If you like R&B ballads, check out Miliyah Kato, Thelma Aoyama, and hiromi. Maybe YU-A.
For more pure hip hop, you might like yu yamada.
miray is good for like...bubblegum hip pop lol
mini is good for dance music. She's a newcomer. Been very impressed by her music for a debut.
Lots of hype over JUJU lately as well~
Check out SAWA too for electro/house/pop~ Because I'm trying to spread her around