This year I did much of the following three on the list:
4. Northern Trail (New England)
3. Erie Canal
2. Ohio to Erie
I can see why the Erie Canal and OTET are on the list. Both New York and Ohio have done a good job in stitching things together, adding signage and having links with adjacent businesses.
I found the Northern Trail OK but underwhelming and not really in the same category as the other two. If I were to nominate a replacement for this list it would be the sequence of four trails in Wisconsin: 400 Trail, Ellroy-Sparta Trail, La Crosse River Trail and Great River Trail. These can link together in a ~140 mile sequence.