I'd say #3 fits her more now that the latest manga show that she gets nervous or loudly insecure whenever her appearance, intelligence or simply the subject of love is discussed.
#2 or 3 seems to be the more canon imagery for most characters. But in this case I think 3 and 4 meshes well personality wise and since I'm a sucker for big boobs... 3.5
I-it's fine, isn't it? About this much is fine, but...Dude! You've been staring at my b-... my chest this whole time...Nah...it can't be helped...You're a perv!You like 'em bigger?Nah, the size of my breasts doesn't matter to me.Just for a little bit, okay?Hm? What's up?