If we assume it's in JAPAN, then Oda. But if not then probably Emiya, though Oda is still very powerful servant

But would Nobunaga be able to affect EMIYA? Nobunaga's Noble Phantasm is specialized for battles against Divine Servants, which EMIYA is not. And since EMIYA is a modern Servant, Nobunaga's skill also shouldn't work to a significant extent.

Oh right, kinda forgot about that part

Yeah, with Demon King of the Sixth Heaven and Unifying the Nation by Force both being powered by the Mystery and Divinity of a target EMIYA is an unfun opponent for Nobu. Even Three Line formation wouldn't do much since it scales off of Unifying the Nation and the target having Riding, which EMIYA doesn't.

Emiya is her worst possible opponent. He outclasses her physically and skill wise so he dominates in close quarters, his own spam can counter hers, he has more one shot options, and literally none of her buffs trigger against him, which also means that in a clash of reality marbles it'd be UBW's A++ to DKotSH's E-C at best.

This is an extremely interesting matchup. Nobunaga even without mystery boost is an absolute DEMON. Remember that Okita is a very modern servant. She however actually fairly counters his weapon spam. She's just going to spawncamp his weapons with 3 line, but he has a lot going for him in his own instance, of being faster and overall an actual fighter.

Nobunaga is much smarter, has faster weapon dial up, and EMIYA doesn't have the projection durability to tank her shots, or at least to avoid being knocked off course. Emiya is Faster, stronger, and a much better fighter with more options, but Nobunaga's faced all of these with relative ease.

I think it really comes down to RM's and the range distance, (RMs he just wins in). At long range he also wins due to broken phantasms.

At mid range, Nobunaga wins, and is going to just range him out by levitating out of his reach and stopping him from being able to attack properly, and at close range, EMIYA wins via just, being more physically adept

MOST fights, are going to come down to that Mid range, but I think EMIYA wins enough scenarios to give him a very close win