How long is the ride? Having done some intense PBR research (roysearch?) last year, I came to the conclusion that the 20 minute call from the May 14, 2002 show is the call I'd use to introduce the character, since it sets up a ton of who Roy is and what he's going to be doing for the next few years.
My favorite, though, is the two-fer from the 3/29/2005 episode (my usual pick for the best Best Show episode), which has the call from actor Jeffrey Ludell and follow-up call from Roy about Roy's movie, Philly Fever. They add up to a little over a half hour, I think.
That said, I don't know if I can disagree with the one that helped get things rolling back on Page 1, the call that would make it onto THE ART OF THE SLAP about Roy Jr. and Laser Allin.