You do realize that Cloud was not "emo " or depressed in the original game right ??
Of course I do. For the most part, he had zero personality in the original game. I get that he got his memories mixed up with the stories Zack had told him, but it doesn't explain how he became indifferent to everything that happened around him. As long as he got paid, he couldn't have cared less if he was going to save the world or not. That makes him a puppet. But for some strange reason, he cares for Aerith, despite not having met her before nor having a clue about their mutual connection with Zack. At the same time, he completely ignores Tifa - his real love interest. Even after she helps him recover his sanity, he treats her like filth and makes it his mission to avenge Aerith, a person whom he didn't even get to know as his true self. How about just saving the world, Cloud?
It's not until after beating Sephiroth that he finally decides to court and eventually settle down with Tifa, the one person who knows him the best and will support him no matter what. And guess what happens next? He disappears, leaving her and the kids extremely worried about him. She deserves an award for sticking with him until the very end, when he finally, or at least hopefully, realises what a tool he has been. Zack and Aerith had minds of their own. They knew what they were getting themselves into. The people Cloud let down were Tifa, Marlene and Denzel. He was too busy feeling unnecessary guilty and worthless to appreciate his friends and family. Not even after what they had been through together.
Zack on the other hand cares about his friends, and is obviously willing to risk his life to protect them, but is also very likeable in general. You get to see him gradually mature in Crisis Core and become a more serious character, without losing his heart in the process. Cloud went from being a mindless drone to being a selfish jerk who put very little logic into his decisions. I like that they at least tried to give him somewhat of a personality as a young kid in Crisis Core though. I wish they had thought of this earlier and incorporated traces of it in all of the games.
Tifa truly is the rock of the entire party, but unfortunately her role is often downplayed by her appearance. I'm really glad they re-designed her for Advent Children. Anyway, she deserves some recognition for being more of a leader than anyone else in the group. It would have been more interesting if they had pulled a Final Fantasy VI in that regard, letting the player think of Cloud as the main character only to shift perspective halfway through the game. Then again, that would have made it incredibly obvious that many of the key elements were already recycled from that game (although VII for the most part made everything better, imo).