It's interesting how opinions vary with age. Whichever film one saw first, as a child, seems to set a marker for them. I saw AHN in 1977. I was 11. I waited desperately for the following two films and ate them up with a spoon. I loved VII because it was the story and style I knew and wanted. I despised Ep. I-III because I felt cheated and let down by something that was very dear to me but I've heard plenty of people over the years who saw I, II or II as children say it's their favorite trilogy. In fact one seemed to be popular with smaller children of the day probably because of the pod race and silly characters.
I suppose it's all relative but even when I try to take my bias out of the equation, I still see Ep. I as an abomination and II and III as justifiable backstory but with little entertainment value.
I agree with those who said to suggest IV, V, VI and VII in that order and omit I, II and III as they don't "feel" like Star Wars.