I do feel the original telling of Zack's death is the best. Its shocking and brutal, making it a lot more tragic IMO. I saw that first so I'm definitely biased though.
I have noticed actually that whichever version people saw first tends to be the one that they're most attached to. That's really interesting to me. I wonder how I would have felt if I had played Crisis Core first.
I'm on team OG.
CC was the one thing that made me cry more than any piece of media has ever made me cry (for complex reasons that would demand their own post). I found a lot about Zack's CC death absolutely brilliant, the way you can feel him breaking down, falling apart. It was a new sort of experience for me personally, seeing someone really use the personal connection you feel with the character you're playing as in a video game in that way. The way the HUD starts to fall apart and you find it more and more physically difficult to fight. You can feel the life leaving him and it forces you to keep fighting against this death you know is unavoidable (assuming you played FFVII first).
I think this all was definitely worth something to me, and I'm glad they did it the way they did, but I have a different sort of respect for OG's portrayal that I think is absolutely crucial to that game.
I think a lot about Sakaguchi's explanation for why Aeris's death was depicted the way it was, and how that made her death really memorable and painful for so many people. I can never find a quote on this when I need to, but he says something about death being sudden and leaving you with a feeling of emptiness. Contrast that with the melodramatic deaths you'd normally see in video games, anime, or other types of big, surrealistic, fantasy/sci-fi stuff. The kind that actually, that they poke fun at in OG with Cait Sith's "death" in the Temple of the Ancients, just to slap you in the face with Aeris's death soon after.
Video games are all about making people seem a lot stronger and a lot more important than we are. It's deeply painful and terrifying to be faced with our own insignificance. That's why we love escapist media where we can watch, or even roleplay as, characters that appear human but are operating on an unrealistically high level of physical or intellectual power (which isn't to say we don't also love vulnerability and relatability, and that's where characters like Cloud come from - “Just when you thought he was cool, he'd do some damn fool thing. Then when you thought he was smart, he'd show how stupid he was.”).
Anyway, even though Zack and Aeris's deaths in the OG both contradict how the universe depicts human strength on the battlefield, I still really appreciate it on its own. This is a game where in battle people can take tons of bullets and giant sword wounds and still fight, but in the story they are much more realistically fragile. I think that's far more painful to watch on a really deeply felt level than the over-the-top hero's death Zack was given in Crisis Core. That melodrama may have made me cry harder, but it doesn't linger in the same way.
FFVII intentionally tried to depict death in a different, and more personally felt way, than other pieces of culture, and it's really well regarded for that. Even though that's related more to Aeris's death and I would be really surprised if they changed her's, I think that Zack's death was definitely in line with everything they were trying to do. It's small and it's sad, it's quiet and fast, and he's forgotten and left behind. There's no deathbed dialogue. They actually continue shooting Zack after he's down just to really make sure he's dead. It's very hard to watch.
I think Crisis Core's Zack death is valuable and interesting in it's own way, but I hope it stays in CC because it ain't FFVII.