Hal9000 for the Prequel Trilogy, and adywan’s Revisited Edits for the Original Trilogy are the standouts / must-watch for me.
The ADigitalMan Saga Edits (Episdoes 1 to 6 and a ‘2.5’ Clone Wars) are well worth a look at as well.
There are a few other ‘which fan edit is best?’ and ‘recommend a Fan Edit?’ type threads listed in the Star Wars Fan Edits & Projects Index (towards the bottom of the index) - which may be of use / interest too mate.