I have tried both and also tried both Legion and Stormcloak, mostly to see both sides of the argument. But I will never be a Stormcloak again and always follow Hadvar at the beginning now.
I think Hadvar would win because he seems more focused and disciplined. Plus I remember when playing through the opening Ralof took a knee twice and Hadvar never has.
Overall I favor Hadvar, Ralof is alright but Hadvar seemed even the first time I played skyrim liked a decent guy. He has his head on straight and acts responsibly and dutiful even in the face of this spontaneous dragon attack and tried to show mercy where he could. 10/10 what a true legion soldier should look like.