While Tifa took up a vendetta against Shinra itself, helping to blow up two Mako reactors and killing hundreds of people...
Which gives rise to a new argument: Kefka VS Tifa
We never see the *fictional* people that Tifa kills with those explosions. I would argue that they really don't matter any more than the thousands of nameless people Kefka kills. I suppose you could use that argument to reflect Tifa's character, and how Aerith is more docile. But Tifa was a determined woman with an ultimately-righteous mission. All Aerith is doing is hiding from Shinra, at first.
Also, there's nothing Tifa could do to help Cloud when he fell from the reactor, and she was very concerned when it happened. Not to mention that she stayed with him throughout his sickness,
tried to rescue him from Ultimate Weapon's attack on Mideel, and, most importantly, helped him to reconstruct his sense of identity. If it weren't for
that, Cloud would not have stopped Sephiroth's Meteor, and Aerith's Holy would've proven useless.
(So now I find myself arguing
for Tifa
I'm a very fickle guy.)
