This might be hard to articulate but - it's very obvious that the most "popular" half marathons are correlated with those that have the most runners not those with the better courses, experiences, etc.
If you're traveling to Colorado, more people have run the Denver Colfax Half Marathon.
But, go ask any avid runner (or someone from Colorado) and they'll tell you to run Horsetooth or the Fall Equinox Half is lightyears better.
I want the hidden gems, the "insider's" recommendations when it comes to half and full marathons across the country (or world for that matter).
A few that come to mind:
The Mistletoe in Winston-Salem
Horsetooth or Fall Equinox Half in Colorado
Top of Utah or Ogden in Utah
Hidden Gem Half Marathon in Flossmoor, Illinois
New Bedford Half Marathon in MA
Wineglass in New York
Jackass Half Marathon in Idaho
Obviously, these are all still pretty subjective but what are the races that avid runners recommend as the "better" ones than the commonly cited ones.