The affection stats seem to be deliberately set up so that you'll get Aerith all or most of the time, if you really don't bother to try. But that's just an impression.
There's so many little, unrelated things that can influence the outcome -- who you talk to first after the Don dumps you in the sewers, what you say to an NPC in Fort Condor, what you say to an NPC in Kalm who talks about mako energy, who you take with you to see Dyne, etc. -- that it's difficult to say.
Something as simple as favoring having one of the women in the party over the other might ultimately prove to make the difference by a couple of points -- and, of course, who you have in the party might have more to do with who you find more useful in battle than who you would prefer for Cloud.
NB said:
As for how Cloud's feelings factor into this, I've always & continued to maintain a neutral stance, but it's very difficult not to admit that there are some pretty heavy-handed "he loves Aerith" messages throughout the game. That said, regardless of who's "right" for whom, barring the variable of the affection scores, Cloud seems to have been paying more attention to Aerith at the time.
I disagree with this for the simple fact that all of those things are determined by the player. Really, aside from Cloud caring about Aerith's safety and emotional well-being -- which he also demonstrates for Tifa -- there's nothing resembling romantic interest that he ever expresses toward or about her that isn't determined by the player.
Even on the date with Aerith, one can choose to have Cloud say he didn't enjoy it.
What one thinks they see as Cloud expressing interest in or especial concern over Aerith is more than likely an impression left over from how they themselves treated her.
That said, I don't doubt that he was attracted to her.
NB said:
But really, you're missing the point. Just because you can do it that way, it doesn't mean it's as good of a set-up.
It depends on what later event you're looking at, really. Aerith's date sets up the reveal that Cloud isn't himself, but Tifa's date serves as a good bookend to her later successfully being honest about her feelings for Cloud, and getting him to do the same about her.
Really, both dates serve as useful thematic tools.
