I did not have the privilege of watching Jerry Rice through his prime, only towards his later years (when he was with Oakland, Seattle).... Randy Moss in his prime was a beast... maybe my opinion is biased because the main games I watched him in were against the cowboys, and he was unreal against us. I would say he could challenge Rice to be the best, but look at the teams they were on. Quarterbacks alone, Jerry Rice had Joe Montana and Steve Young.. When Moss had a good quarterback (no, I don't think Daunte Culpepper was a good quarterback), he was on a team that put up points like no other, and went 18-1 only to lose in the superbowl with the patriots....
Stats are a foolish thing to base status on... and Rice's argument was to compare the stats.... Moss' argument is to compare impact on the game... Moss was a selfish player in his earlier years and wouldn't run a route if he knew the ball wasn't going his way, and was a poor run blocker... but as a straight up receiver, Moss demanded double, triple coverage sometimes, and even if the ball was near him he'd catch it.