Yule, I have had a lot of LLCs including many of the wines listed and there is a lot more to this than just old methods vs. new methods. I never found the 1970 to be a great wine. This was an unusual vintage where both Poyferre and Barton were better than LLC. By contrast the 1975 has been fabulous when I have had it. Vince’s note on the 1978 is much more positive than when I have had it, but the wine was always good and I have not had this vintage in a long time.
As for the great vintages of the 1982-1990 era, a few years ago I had the 1985, 1986, 1989 and 1990 together with friends. A lot of the differences in these wines were with the vintages, not the wine-making IMHO. The 1986 and 1989 had a wonderful combination of richness, acidity and complexity that I loved and I ranked these two above the 1985 and the 1990, which were rich but a bit soft IMHO. About half the table agreed with me and the other half preferred the lushness of the 1985 and, esp. the 1990. I think all four vintages were very representative of their vintages. [By the way, my favorite of this era was the 1982. Long closed, but now starting to show the promise the wine showed in the mid 1980s. I have one more bottle.]
The 1996, as Vince said, is just a great wine. It also is the youngest LLC I own. The wines take a long time to age and I am aging faster than they are.