I have read Luffy combat inteligence (again) and while he is very good, I think Asta has a combination of traits that could give him the victory
Luffy for example found ways to defeat Enel even with his early Haki advantage, problem is that Enel needed to predict his attacks and Luffy found ways to capitalize that, but with Asta, who is not predicting attacks but rather is sensing a energy made by movement, emotions etc, there is no way Luffy can throw off him
Luffy initial and probably superior for the rest of the fight because both could grow up during this fight Ap advantage, would not be super useful because Asta can decrease the potency of attacks he recieves, meanwhile, Asta is exploiting his weakness and while no one had the ******* idea of attacking Luffy limbs while he is streching (except Mihawk for what I remember, because he is a chad), Asta with Ki, could counter him
Luffy however, could just overpower Asta with his superior LS and could BFR, Asta then must return to the battlefield and can perfecly do that with his stamina, he run from the Black Bull base to his village in less than a day, if he lands of water then is gg for him, this depends of luck to be honest
Both can mimic, but because I think their entire combat kit is different and Luffy has never mimic a swordman, while Asta has never mimic a brawler, this is useless or both mimic eachother and is pointless
So, because Luffy with Haki clearly would just be a better Asta, he would just win, but here without Haki, Asta is basically an Enel that is at least 75% as skillful as Luffy, and is using his weakness rather than being the one countered
Even worse, Luffy trying to predict Asta could end in him recieving a free hit because Asta has movements that are unable to be read, this is different from Kuro who is attacking randomly
I think Asta wins with high difficult, 5.5 out of 10, both almost has the same powers but Asta having Ki while this Luffy is not using Haki yet is the main difference of why Asta can win more often
PD: And I thought about "But what if Luffy mimics Ki"
Why did Luffy not mimic early kenbushoku Haki from Enel then? Luffy would need to learn how to sense movement energy and read emotions, the funny thing is that he can already "read" emotions with the voice of all things, but that works more like he can just "understand" animals and is extremely rare when he use it
Finally: Luffy has good stamina, but Asta fought zombies for hours and can fight even while at the brink of death, so both are extremely similar, with Luffy having an edge if anything (I am not counting Impel down+ marineford, with that, Luffy is superior by far, but this is Water 7 Luffy and we don´t scale Zoro's stamina from Thiller bark to his earlier keys for example)
