Classic James "Logan" Howlett: gruff and tough. Note that when he shows up in alternate timelines he appears a bit older. Not Old Man Logan old, but he has some grey hair so keep that in mind. For the voice the best suggestion I have is something along the lines of Steve Blum's voice as he's the most well known Wolverine voice actor, though if you want to go in another direction we'd be happy to listen to it.