The Empire Strikes Back
Return of the Jedi (I only put this above A New Hope because of the golden bikini and the ending)
A New Hope
The Phantom Menace
Revenge of the Sith
Attack of the Clones
I haven't seen the rest and I don't care. It's obvious Lucas was embarrassed that after Empire became so successful and his wife started blabbing about how she saved the first one through editing he panicked and tried to rehash his toys and pretend there were some hidden meaning behind them. You can see this in Return of the Jedi. Death Star is back, more speed racers, more puppets, more lightsabers and less actual character development.
When the Phantom Menace came out it looked like something George was originally planning where some weirdo befriends puppets to fight a war while he defeats the bad guy/saves the queen. Everyone hated it so he tried to copy Empire and failed spectacularly, so Revenge of the Sith came out and as far as I can tell, people only liked it because Darth Vader was in it. The rest is just filler.
As for the sequels, they're doing the same thing of shoving shit in the frame to sell toys to kids but focusing on the things people liked from the original trilogy (specifically, Luke, Leia and Han). Unfortunately, they made the same mistake by focusing on the toys and not the characters.