King Ghost rider slapped around Dr strange, broke Mephisto out of hotel inferno with ease. I thought that would make him pretty strong. Deadpool said king of hell spawn stomps ghost rider tho. That's what makes him seem overpowered.
Well, he obliterated and recreated the universe but yeah.
Both of these versions are the most powerful versions and as far as Spawn goes, was never seen again to my knowledge.
We usually blame this on writers writing themselves into a corner as far as power level goes but in all actuality they are just trying to appease fans and human beings in general seem to get bored easily with things so they feel the need to constantly get bigger and flashier.
Half if DC is on a multiversal scale somehow but they somehow keep being "threatened" by beings that are somehow more powerful.
Or the opposite route Marvel made Thor strong enough to one shot a being that destroys universes but he damn near got ktfo by a thrown rock. Horrible writing.
Currently, Spawn is wrestling against the demons and angels that he trapped on Earth. He thoroughly worked an angel and had the power to shield nearby innocents from the ppower being unleashed within the shield, before defeating the angel. It's a bit difficult to gauge exactly how powerful Al is ATM, but over the past 100 issues of his ongoing series, I'd say that he could very well be more powerful than Hell Lord Ghost Rider.