I know it's the guy from The Witcher 2 who's going to reprise his role, but one can dream...
And I have a perfect suggestion: Michael Wincott who's actually Canadian, but never mind.
He is a fairly recognizable actor who had played major roles in movies like Alien Resurrection, Jim Jarmusch's Dead Man (with Johnny Depp, Lance Henriksen, Iggy Pop, John Hurt and others), The Crow, Strange Days, Robin Hood: Prince of Thieves, Basquiat, Before Night Falls, The Doors, The Three Musketeers, and so on... and is going to play in the sequel to TV series 24: Live Another Day.
Anyway, he's also played in a fair share of video games, such as Halo 2 (Prophet of Truth), Darksiders 2 (Death) or Syndicate (Agent Jules Merit).
And it's the latter which is going to serve as a sample of his voice for you, fast forward to 6:55 and listen to it for a while, or fast forward to 21:40. His gravelly voice would be so good for Geralt! Of course in Syndicate he is very cocky, and he wouldn't be like that as the Witcher and his voice in Halo 2 or Darksiders 2 was way different, but this is closer to his default voice:
In the end, it's not going to concern me much since I'm going to play the superior, original Polish version. (Polish dubs are ALWAYS way inferior but The Witcher is the only exception).