I've always leant more towards ROTJ as being my favourite; Jabba's Palace, the Rancor, touching scene with Luke, Yoda and Ben, the big space battle over Endor and the final confrontation with the Emperor.
It's just a nice comfortable sort of film to watch and even better without some of the changes. I have to say I wasn't a fan of putting Hayden in at the end or the beak in the Sarlacc pit, but the musical number in Jabba's Palace was brilliant.