It's not order, it's number of frames...
"Tell me what you cherish most... Give me the pleasure of taking it away..."
4 frames - Aerith
4 frames - Aerith flying in (a cut-in real time to show she is on her way to help?)
4 frames - Tifa
4 frames - Marlene
4 frames - Denzel
12 frames - Zack
Cloud loves Zack times 12 - and he saved the best for last
My gawd I realized in Crisis Core when Zack was dying all Cloud thought about was ZACK. There is a whole montage of his moments with Zack in the song and that was the most number of flashes in FFVII!
Then look at the last battle of Crisis Core:
First to be shown is Cissnei, Tseng and Sephiroth, then Cloud and Angeal then Aerith!
We all know Zack loves Aerith! You always love the last!
To further prove my point remember the ending of FFX:
Yuna says "the people and FRIENDS we have lost... and dreams that faded" and the people who flashed are in this order: Kimahri, Rikku, Lulu, Wakka, Auron, and HER KISS with SEYMOUR, then Tidus has the longest.
But nevertheless Zack is in the same place at Tidus, the last spot AND the longest flash. If we use the last is the best logic, then her kiss with Seymour is more important than her guardians!
I actually have more examples from anime, where the most important person is always reserved at the last place with the longest frames.
Clack is canon
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To change my topic a little, Cloud and Tifa actually shared way more smiles than Clerith.
He lifts a collapsed Tifa up in his arms, and upon seeing her aware of him, he smiles gently.
-Cloud Strife 10thAU profile
As Tifa looked away from the sky towards the ground, she was fearful of the future. However, Cloud beside her chose to smile gently. It was a smile that she hadn’t seen before during their journey. Cloud noticed her gaze and asked, “What’s wrong?”
“Cloud, you’re smiling.”
“Because I have you this time.”
“You’ve always had me.”
“What I mean is kind of different,” Cloud answered with another smile.
“Aerith brought Denzel to our home.”
Cloud gazed at Tifa and finally smiled.
It's false thatCloud only ever laughed with Aerith, it's true that it's theonly instance in the game, but his profile made it sure to mention "while he's under Jenova's control."
Cloud laughed with Barret and Tifa here:
Tifa and Cloud sipped their alcohol slowly. Barret was drinking so much that you could probably bathe in the amount he drank. He looked like he was enjoying it and talked about his memories of peaceful times. Drunk, he fell into a well and spoke nonsense about proposing to his dead wife. It had been a long time since Tifa and Cloud burst out laughing.
In Advent Children Cloud smiled to Tifa twice, and when he smiled it was only to her and her alone.
Bahamut hand reach scene, the only one he smiled for.
And the ending scene in AC, where personally I find it that he looked for her so he could smile to her.
At his last smile Zack is always ignored, Cloud was smiling at Aerith AND Zack. Geez.