Tate
Floyd
Shark
It's all very close for me. All the career records for Floyd are meaningless as it relates to this order. Besides, there's a decent chance that if Tate came back for his Senior year he would hold some of those records.
Tate came in and had to spend virtually his entire Freshman season learning to play the WR position. Floyd came in as a Freshman college ready. What Tate did his Jr year at ND was crazy. Floyd had the better overall career, but the list isn't asking for that.
Who would I take into battle? While I believe Floyd and Tate were really close, I believe that Tate had surpassed Floyd as the top receiver when he left.
Floyd over Shark for many of the reasons that others have pointed out.
Others will rank them differently, and that's OK because they were all great.