Tough question. I think I have Moss as my #1 ever, but I am conflicted on where to rank everyone else. Edelman's got to be in that top 5 though, somewhere with Troy Brown, Deion Branch, and David Givens.
Actually screw it, let me try with a top 10 from guys I've watched play:
1. Randy Moss
2. Troy Brown
3. Julian Edelman
4. Deion Branch
5. David Givens
6. Wes Welker
7. David Patten
8. Terry Glenn (yup I'll be the first to show him some love, he was exciting to watch early in his career)
9. Brandon LaFell
10. Danny Amendola (I admit the past month is the only reason he makes it this high)
Honorable mentions: Shawn Jefferson, Jabar Gaffney, Donte' Stallworth, Vincent Brisby