The actor is important but I feel there is another critical component that is being neglected in these discussions.
Wolverine's body movement during combat.
No matter which actor you get their berserker rage will still have human qualities therefore it will look the same as Jackman's which is slow and lumbering.
Arms will still look like arms, swinging away...just like Jackman.
There needs to be a change in that.
I want to see the live version of the Capcom videogames.
I don't know, explain it that when he goes into rage mode his mutant powers give him super speed.
He needs to almost be a blur during his berserker rage scenes so that they stand out as something unique to his character instead of just a guy who can swing knives around like any person holding a kitchen knife can do.
He needs to be more than just pturtle holding a knife yelling like a mad man.
He needs to be a super (fast) weapon.
Or else no matter the actor....it will be "oh look he's swinging his blades around just like Jackman"....yawn.
Also make him a special attack character, no more the primary focus.
He should be a combo of Billy from Predator, the sniffing barbarian (Franco Columbu) from Conan the Barbarian and the shape from Halloween 1.