The best Tifa design, you ask...?
For sure it's from the animations of the original game (and menu screen)! I really can't understand this somewhat cowardly attitude resizing her boobs and all. I mean, if somebody has big boobs what is the problem? We have to think what kind of an image we are trying to give our children! We should accept the people as they are or as they are born, not how the public at the moment happens to like it. God I loved Tifa only for her boobs and after I saw what they did to her, I just couldn't care less about her anymore. After that she was just another shy girl with fucking traumas. It's the same thing in real life: if somebody is full of shit, you at least tolerate him/her better if she/he looks good.
If you had to describe every person from the original game with just one word that first comes to your mind, how would it look like? I'm talking about characteristics or appearance. Well, I can do it right now.
Cloud - Cool
Barret - Big
Cid - Tabak
Aeris - Lovely
Yuffie - Bitch
Nanaki - Dog
Cait Sith - Cat
Vincent - Scary
Tifa - Boobs
Okay then, let's continue. Now we try a variant, one can only try to say the dominant characteristic of the character. Of course the first one that comes to mind. Ready?
Cloud - Strong
Barret - Badass
Cid - Motherfucker (in a good way)
Aeris - Unbelievable
Yuffie - Annoying
Nanaki - Deep
Cat Shit - a piece of catshit
Vincent - Emo
Tifa - Ehm, what? Main characteristic..... Can I say boobs?
See the point I'm trying to make?
PS. I should really stick to the one sentence answers.