Lord Shaxx beats them both and gives ikora some ass whopping too

Cayde got tackled out of his golden gun by the equivalent of a dreg, and also got stuck in a vex teleporter. He was getting manhandled by low tier scorn. I doubt that he is beating Zavala.

If the competition between the two would have been on pure strength then I would say Zavala, but if it's a fight to the death, I would put my money on Cayde. Zavala doesnt do well with losing and although Cayde himself admits to being a sore loser, Cayde has had to adjust his style of fighting to match almost any situation, this is especially based on the fact he spent a lot of time in the wildest, where as Zavala spent the majority of his time in the city, building, maintaining and watching over the walls. He most likely is used to the rules of engagement like those in the crucible. In this way he thinks on his feet sure but not to the same extent. If you watch the last stand trailer you can really see that Cayde was very good at anticipating and adapting to his environment, often using it to his advantage. Plus in a fight to the death there really is no rules so cheating is entirely on the table, something we know Cayde is very very good at. He knows he can't take a titan head on but he can though other methods. So TL;DR Cayde is a lot more adaptable to situation and most likely had a lot of life and death situations.

Cayde, pops Goldie and Snipes Z across the map with it