It's tough to know, because not many people lived throughout every generation. My buddies dad is huge hockey guy. I believe he's 55 years old. Has center ice, played junior hockey, runs competitive hockey camps, etc. This guy is a bruins fan.
I asked him where he thinks karlsson is, he said he thinks he's better, but very similar to coffey. What i remember of coffey is like mid 90s and on, so i'm not the best judge. But in terms of rushing defenseman, he thinks there is Orr, than after that its debateable and karlsson will be in the conversation. He didn't compare him to bigger guys like denis potvin as they played totally different styles.
I know you're thinking "so what, some guy can think anything he wants" but i really trust this guys knowledge.
I see karlsson as clearly the best skating,puckhandling defenseman since the 90s. He thinks he's more talented than leetch, niedermayer, housley,coffey, murphy, etc. I put stock in that.
So really, the only guys i don't think he'll pass are guys like:
Orr
Bourque
Potvin
After that you get the guys i named and guys like Robinson,chelios,macinnis, Stevens, etc. There is no reason karlsson doesn't belong with them when all is said and done.
http://www.quanthockey.com/nhl/records/nhl-defensemen-all-time-points-leaders.html
When all is said and done, can you name 20 D on that list that are better talents than karlsson? I mean, i know this is scoring, and there is defense to consider, but when you have guys like chelios at 10,stevens at 12, gonchar at 16, duchesne at 20...karlsson is undoubtedly a better player than them.