HBK/HHH from Summerslam 2002 & HBK/Diesel from Good Friends, Better Enemies are extremely overrated. But the most overrated match of all time has to be RVD/Hardy from Summerslam 2001. I've seen people give ****+ to that match, when I thought it was about * max (I actually gave -* because of the blown spots). It was an awful match. RVD matches in general tend to be really overrated.
HBK/Jarrett is Shawn's last truly great 'wrestling' match, but tends to be forgotten for other, inferior, stuff later on, so I will say it is underrated despite most people giving it high ratings. Malenko/Benoit at Hog Wild is underrated because too many people rate based on crowd noise rather than the actual match.