Moss and the reason is simple. Moss was able to do in Wash, what several other (supposed more talented players) couldn't and turn around a dead passing game. He is a marvel of a deep threat given his size and his ability to stretch the field creates huge mismatches for everyone else on the Wash O. While S.Smith is a bit more flashy and more explosive, MM was able to have a very similar effect in Car while nobody else has come remotly close to the impact that Moss has in Wash. There is very little seperation between the 2 players IMHO, but I have to give the tie breaker to Moss given the cercumstances.
How do you think Steve Smith would do in Washington? My guess is that he'd do just fine... dare I say better than Moss. Smith's strength and running ability after the catch are second to none.Also, Moss had one 74 catch season in the past, including a 45 grab year last year. Not exactly what you'd call 'turning around a dead passing game.'
Finally, MM is a darn good receiver, so that you can't just say that whoever replaces him as the #1 in Carolina is going to lead the league.
My 2 cents...