In terms of WR its really Rice, Moss, and then Owens. Owens is 2nd all time in yards and 3rd all time in TD's. The players you mention were great players, but to be top 3 at your position ALL TIME and not be a first ballot HOF is laughable. IMO. Megatron was awesome. But IMO part of being at a Rice Owens Moss level is the ability to do it over a long duration of time. Megatron didnt. He falls a bit short of that level