Actually, this will be a relatively short article, believe it or not! Most sites dedicated to Tifa/Aerith sport pages upon pages of reasons to support who Cloud should be with. If you want to view these reasons, I have links that will take you to sites that have these reasons. Here, I'm simply going to state the simple facts... BOTH had an equal chance to be with Cloud! Why do I say that? Well, notice throughout the game you can make certain choices that favor one or the other. In a sense, you can chose who Cloud prefers. That SHOULD make everyone happy, but for some reason, it doesn't... o_O *sighs*
I hear a lot of "Square said this and Square said that..." about who Cloud was meant to love, but, no offense, I think most of that is bunch of bull... It's obvious to me that it's your choice. I'm sure there are convinceing arguments to support either side, but, though I prefer the Aerith/Cloud combination(don't hurt me!), I admit that it could have easily gone either way! And that's just the way it is!