Yes, I agree. The idols like Morning Musume or Hello Project never had good singers like Ran, Miki and Sue and never sang in those beautiful harmonies that Candies did. They really are hard to beat.
In all honesty, I've watched hundreds of idols, from all eras, and the Candies are still hard to beat to this day. The voices, their harmonies, their lookm, their playful music and melodies. And when I think about all the daily hardships these young girls had to deal with, it makes their performances even more impressive and touching. They are the Queens of Idols.
I agree with all you say, I think you have described exactly what Candies were. For me they are one of the best vocal singers ever, of course they were more than an ídol group, hard to beat by the other idol's groups. Ran was a great, very great singer, and Miki and Sue were great un harmonies. Yes, Candies forever!