ESB
ANH
ROTJ
Going Back to Highschool
Doing Homework
Getting a Wedgie and then a Swirly
Getting Punched in the face
Getting strangled to death
Watching my wife and kids brutally murdered by people in clown suits while they pour melted wax on my arms and legs, and then rip my hair out.
Then a three way tie between 1, 2, & 3, assuming someone actually made Star Wars Prequels and they were as terrible as I assume they would be. ;)

But here's my non-hyperbolic interpretation of the Prequels: As far as quality goes, RotS was the best, AotC was 2nd, and TPM was the worst. HOWEVER, how good each film should have been runs the same way. TPM could have been "meh" as long as AotC was "pretty good" and RotS was "AWESOME!" But TPM failed to reach "meh" and AotC was merely "meh" and RotS was maybe a hair above "meh." Therefore, RotS is the best AND the most disappointing, AotC is 2nd best and 2nd most disappointing... and TPM continues to fail at being 'meh.'