I'm honestly not sure, it would be a hell of a fight but seeing as I have Fall of Reach sitting in front of me here's an excerpt from when they were enhancing the Chief. Keep in mind that Spartan 117 is the most genetically perfect human being out of a massive human population of around 20 billion and has been trained rigorously from the age of 6 (he is 14 when the enhancments are made):
1. Carbide ceramic ossification- advanced material grafting onto skeletal structures to make bones virtually un-breakable.
2. Muscular Enhancement Injections- protein complex is injected intramuscularly to increase tissue density and decrease lactase recovery time.
3. Catalytic Thyroid Implant- platinum pellet containing human growth hormone catalyst is implanted in the thyroid to boost skeletal and muscle tissues.
4. Occipital Capillary Reversal- submergence and boosted blood vessel flow beneath the rod's and cones of subjects retina. Produces a marked visual perception increase.
5. Superconducting Brification of Neural Dendrites- alteration of bioelectrical nerve transduction to shielded electronic transduction. Three hundred percent increase in subject reflexes
Also here is another excerpt from the book. Keep in mind this is all without their mjolnir suits and when they were only 14:
"Your Spartans can run at burts up to fifty-five kph," he explained. "Kelly can run a little faster, I think. They will only get quicker as they adjust to the alterations we've made to their bodies. They can lift three times their body weight- which, I might add, is almost double the norm due to their increased muscle density. And they can virtually see in the dark."
Dr. Hasley pondered this new data. "They shouldn't be performing so well. there must be a synergistic effect brought on by the combined modifications. What are their reaction times?"
"Almost impossible to chart. We estimate it at 20 miliseconds," Mendez replied. He shook his head then added, "I believe it's significantly faster in combat situations, when their andernaline is pumping."
By the time the first game comes along the Chief is light years more advanced than in that excerpt through a combination of battle experience, Mark V Mjolnir and Cortana optimizing his neural pathways making him even faster and smarter.