I agree with Mamuang, Matt, and Clark about Magness, Harrow Sweet, and Korean Giant being the top 3.
Yoinashi- Good, traditional Asian pear, not as good as KG, but worth growing
Jilin- Haven't gotten fruit, but it sounds like an interesting variant on an Asian pear (ARS: https://npgsweb.ars-grin.gov/gringlobal/accessiondetail.aspx?1917811)
Duchesse D'Angouleme- No fruit yet for me. I'd need to hear more from Clark
Rotkottis Frau Ostergotland- No fruit yet for me. Red flesh should look pretty neat, but I haven't had it flower in the 4 years since I graft it. So, it is more like Magness than Harrow Sweet in that regard.
So, I'm not really sure about the last 4, but would probably do the first 2, just because I don't like waiting for Euro's to fruit. Or even an extra Korean Giant.
In what way was the quality low? Bad texture/grit? Not sweet? Bad flavor?
Also, is Duchess the same as "Duchess d'Angouleme"? I looked in Pears of New York and I see 15+ pears that start with Duchess. I suppose I can compare in a few years when the grafts I made from the Duchess wood you sent me fruit alongside the Duchess d'Angouleme from ARS.