Simply who do you think, looking at every aspect, is more talented.
True but it's quite hard to differentiate them as heels because their best work as heels were almost polar opposites. Eddie was the legit madman, boarderline psycho, look at his promo when he was clutching onto Rey's mask. Jericho was the pompus, smug heel who'd kick you when you're already down and take all the credit, where Eddie would go and get a chair and hit the shit out of you whether you were down or not. Both played them amazingly though.Eddie is better in every area except mic skills, and even there he's pretty good. Charisma is a toss up. In ring, I'd say Eddie. Better face is easily Eddie. Jericho is a crap face, his character bombs every time he goes face with the exception of the Attitude Era where he was allowed to cut loose more. In a more restricted environment he sucks at it. Better heel is also easily Eddie. I'll say that Jericho is the more entertaining heel, but Eddie as a heel could not be beaten for sheer believability and presentation. He really made himself believable. Jericho is entertaining, but he isn't so good at actually looking like he's a real villain, I just see him portraying a character. With Eddie, though, it really felt natural. Top quality acting for a wrestler.
I prefer Jericho's 2008-2010 run to anything that Eddie has done, but Eddie was a more versatile talent.