The original question was for the most "impressive" WR.
To me, to be really "impressive" when performed, there has to be tremendous excitement or amplitude.
Distance races are out, they are slow and take too long.
For my money, the most "impressive" are probably the PV and JAV.
Maybe the best of all is JAV, the thing is flying 100m! A good JAV toss always is impressive, the flighting, the impact of the spear, the sheer distance covered, sometimes quivering in the air, there is power, suspense, wonderment, it is maybe the best spectator event, and sometimes a ref gets hit.
My vote is for JAV!