Okay, so after looking this over, I'm thinking this is leaning more towards Kenshiro, but with some difficulty. Granted, I don't know much about BlazBlue, but I'll try to explain myself well.
While Ken loses his precog in this fight, he still has instinctive reaction, so it'll be difficult for Ragna to land a hit on him. Not impossible, but difficult.
Because of how Hokuto Shinken works, Kenshiro only needs to land one hit for Ragna to be severely wounded or killed. I don't believe the same can be said for Ragna.
Both can harm souls, and while Ragna can interact with incorporeal objects, I don't think he can hit Ken while he's intangible with Muso Tensei.
Ken has gained a lot of martial arts styles over the course of his journey and can switch to them on the fly. These styles include three different varieties of Hokuto (Ken's, Toki's, and Raoh's), slicing opponents with air pressure (Rei, Yuda, and Souther), piercing and ripping apart the opponent (Shin and Shu), and various ki based attacks, ranging from blades to blasts (Falco and Kaioh). All this variety will keep Ragna on his toes.
Ken has access to the Soryu Tenra technique, which takes two fighters to a void dimension, strips them of all their powers and abilities, and leaves them to fight hand to hand. The loser gets erased from existence. If Ken can pull off this technique and land a hit, I think Ragna will be erased, since all his resistances will be taken away.
The only thing I'm concerned for right now is Ragna's soul drain since I don't know how powerful it is.
So yes, based on the current standing, I'm voting Kenshiro, mid to high difficulty
