I have Harvest,sorry Neil great album if commercial,on CD and Harvest Moon, but will check out more of his 70s catalogue less known
Yes, Harvest is great and I like it too. Same (but a bit less) for Harvest Moon. But they are by no means his best work. I am working on the principle that you can appreciate all styles of music, not just Country Rock.
Recommended albums from the 1970's in chronological order:
After the Goldrush (pre Harvest, young Neil at his best)
On the Beach (difficult and sad/melancholy but also beautiful)
Zuma (the new version of Crazy Horse, the band is back together!)
Rust Never Sleeps (lots of things, but including Neil addressing the emergence of punk in the late 70's)
If you want to go back to the 1960's then 'Everybody Knows This is Nowhere' (1969) is on the same level as the records mentioned above, and features the original Crazy Horse including Danny Whitten on guitar whose death was the reason behind 'The Needle and the Damage Done' off of Harvest.
1975's 'Tonight's the Night' is in some ways the best Neil Young album but is very difficult and raw. It is more or less a live (in the rehearsal space) recording of a wake for his dead friends who overdosed on heroin.
Cortez the Killer (from Zuma)