BLATENT FANBOI ALERT!
[spoiler]Link. Cloud is an assmonkey. :0[/spoiler]
Objective opinion: They're from two completely different games, Cloud couldn't destroy Gannon with the weapons/items found in FF7 and Link couldn't kill Sephiroth with the weapons/items found in LoZ. So that argument is moot.
If you put the two in a death match cage with all the major items from their respective series equiped and removed clouds turn-based gameplay. You have the pay-per-view event of infinity that could only be determined in said cage match in real life. This is never going to happen so the only way to find out for sure is:
a) Pray god answers this question for you when die.
or
b) Ask fanbois what they think and let them argue over it until they die.
Either way the question will never have a conclusive answer in this lifetime.
Essay Pro