The "best" Hall of Fame argument is not always the argument about the best player. Arguments about all-time greats aren't really arguments, just biographies. Great Hall of Fame debates start with players or coaches who haven't achieved legend status: the overlooked old-timers, controversial current players, guys famous for losing Super Bowls, individuals who may have rubbed voters and/or the public the wrong way, and so on.
You won't find many Marvin Harrison-level candidates in this slideshow: Harrison is a Hall of Famer; it's just a matter of time before he squeezes through. There are one or two A-plus candidates here, but we're focusing on the B-plus and even the C-plus guys in the name of having really goodarguments.