my 2 cents:
Randy Moss - The assumption is the players are healthy. Moss and Walker both have attitude problems (Remember the feud between Favre and Walker last season?)
Hines Ward - 30 years old do-it-all Ward vs. 27 years old Walker with attitude problems, I'll take Ward
Roy Williams - 24 years old, His QB is Joey Harrington. Walker has Favre.
Reggie Wayne - more consistent than Walker, who only had one good season.
Andre Johnson - 24 years old, best season: 1142 yds, 6 TD. His QB is David Carr and his team hasn't had a o-line for a long time.