Wow a Junko Thread...
Well, being an avid Tatsh fan, I am also quite fond of Junko, especially her Voice.
I would say she's one of the best BEMANI vocalists, along with Sana and the like.
My favorite song by her, despite all of her works with Tatsh, would be With Your Smile from IIDX GOLD...
Second is Don't Be Afraid Myself... :P