Personally I do NOT like the spelling of
Isabelle. I much prefer
Isabel or
Isobel. I just think the name looks more balanced that way. In terms of phonetics, a very pretty name. I like it. You don't like
Isabel, I know, so I would say go for
Isobel.
Isobel is definitely not overused. I think that thanks to Twilight
IsabelLE might become popular as parents look for names that include "
Belle."