i'd go with Rachel, She's based of spartan who was already a clone of leon/bayman and doesn't really fulfill any unique role gameplay-wise.
It's hard to choose, everybody brings something new to the table. However, even though I love Eliot, I have to say TN still failed to define his individuality for the moment. We'll see in the future.
Gen Fu bores the hell out of me. Individuality-wise I have to agree with Brute, her fighting style is fun and flashy but it's 95% Kasumi
Ein & Hitomi are pretty bland. Leon doesn't seem that special either overall. Though everyone adds something to the roster in some way...
Chapstick is right. Honoka is wholly useless. Unless you count "having slightly bigger boobs and butt" as "bringing something to the roster." In which case I pity you and your low standards.