Well Foley definitely is but he's probably the best promo guy ever.
And after that i'd say Austin is.
Then there's a few guys who i'd say are similar levels to Jericho, guys like HBK, Lawler. All brilliant on their day but capable of cheesy half arsed promos when they couldn't be bothered. Then depending on how far you go back guys like Savage, Ted Dibiase, even Piper on his day.
Like i said, Jericho is very good but no way is he overall better than those guys
And as much as his jacket sucked, 25 seconds in is just pure brilliance.
[video]http://vids.wwe.com/14480/wwecom-exclusive-a-smiling-chris[/video]
Foley is a great shout. Austin, less so

HBK I found a bit limited, but he had natural charisma which shone through. Lawler... I don't really count. He didn't cut many promos as an active wrestler but he was a great colour commentator.
I think you're underselling Jericho to be honest. His Attitude promos on The Rock and Stephanie McMahon were things of beauty.
,they make him out to be one of those type that get's beat up nearly all the match and from no where with one move just win even when it looks a certain defeat,He get's more boo's been a face [good guy] than a heel [bad guy] does