I have been thinking about this for awhile and I have to say Welker without a doubt. Moss's work ethic is trash. He doesn't come across the middle and honestly I dont think even tries unless he's the #1 route. While Welker goes out there and busts his nut sac everyday doing whatever needs to get done. He wil lrun any route, he will run the end around, he blocks corners and safeties that are often way bigger then him.
Fitzgerald is the most talented reciever in the league but Welker would probably be my first choice due to all his various talents.
You would choose Welker over ANY other WR in the league??? Is that you Peter King? Off the top of my head: Johnson, Fitz, Wayne, Moss, Boldin, Marshall, V. Jackson, Colston, Rice, C. Johnson ... I'm sure there are more guys that I would take over Welker.