Let's see my list would be
6) TPM - only a few good moments for me
5) AoTC - Better than TPM but a lot of wasted potential and chopping story telling
4) RoTJ - I might take some flak for this one but honestly after viewing it again as an adult it has glaring weaknesses. Ewoks anyone?
3) RoTS - I thought this movie was actually pretty decent. It had it's weaknesses for sure but overall I enjoyed this move. The action, visuals, music was top notch and acting for me was on the better side of the spectrum overall. Obi-Wan vs Anakin was a fantastic scene all around.
2) ANH - this gets the second place nod just because of nostalgia mostly. It kicked everything off and even viewing it as an adult I love watching this move.
1) ESB - I almost feel compelled to put this first just because of the Luke I am your father part. I don't think any Star Wars movie has anything that even remotely approaches that level of story telling.
I also want to add that I never thought the PT was as bad as other people made it out to be and the OT we generally only highlight the good moments while ignoring the bad parts.