I think there are a few guys better than Hedman.
His biggest issue is he's not fast. He lacks foot speed.
The game has changed. Don't get me wrong he's a good defenseman, but his lack of mobility comparatively to some of these other guys is striking and it limits how he can be used.
While some of those guys are still young and it's way to early to call it. other guys like Josi are clearly better defensemen. He's way more mobile and can do things like jump in on the play where Hedman is to slow to.
Pietrangelo could be in there too. But not with the mobility of say Josi.
He's probably top 5 definitely a top 10 guy. But with how the game has changed he'll never be the best guy in the league simply due to his game and how it's limited.
If some of these guys like Makar, Quin, Fox and Marnio keep up their play, and some of them take on more defensive roles aka 50% or close Dzone starts...then you see Hedman drop way down that list. Because they are so much more mobile than him and they can change the way a team plays.
It's not about just stats. It's about what you can do on the ice.
Karlsson before injuries got him, is what you are looking for. A guy who can turn a game around from the blueline. Hedman will never do that.