Both are probably equal in terms of agility tbh.
Spidey has a durability advantage, and spidey senses. Which also gives him a reflex advantage. He also has the strength advantage here.
However, I'd say Iron Fist probably has a huge advantage in terms of striking power.
I think Spidey overall has the most going for him, but a good hit from IF could end this, especially bloodlusted.
Thanks for reading,
What makes you think Spidey is more durable? Didn't Iron Fist destroy a train going full force at him filled with explosives and come out unsaved? Doesn't he also snatch bullets out of the air and withstand wolverines claws? I would say that Iron Fist has the durability department. And the lethality department, just not quite as agile I would argue, but that is debatable. So Iron Fist would have more going for him. Lethality and durability with extensive battle training.
And Spidey has regularly tanked blows from Lizard, Venom, Rhino, etc etc... durability doesn't matter here. Both can kill each other with a single well placed strike.