The voices for the cartoon were Harvey Atkin
and Robert Tinkler. They were fantastic, although different from the voice actors.
If for some weird reason they ever made a Sam & Max LIVE-Action with Sam & Max becoming humans though, Atkin and Tinkler would be obvious choices, they seriously are the characters.
Harvey is gruff, overweight, balding/bald older gentleman with a laidback attitude and can be dirty (hell, it's a role he's played) while Robert is short, nerdy, but full of energy and can be crazy at a moments noticed as portrayed by roles he's played.
I think either them or the original Lucasarts guys would be choice...but I think if they want to CEMENT the franchise Tinkler and Atkin would be choice and give Sam and Max more character then more traditional voice actors like Farmer and Jameson...
I also feel Telltale should be trying to carve themselves a new place in the market, not be the wake of what was once Lucasarts brilliant adventure gaming division.
That's just my opinion though...