I don't know if it's the best, but this is my favorite by far:
http://dev.maxpreps.com/news/a...9f485a6b7&page=6
This is at a home for retired veterans. It's a beautiful old yard with a great atmosphere. We've been there for many games - travel, HS, and summer. The residents always show up to cheer the home team. They know their baseball and sometimes they heckle a bit, which can be amusing, especially for the younger players. The coolest thing is that after each game the home team, and occasionally the visitors, go in a line through the stands and shake hands with the vets in attendance.
BTW beer is available except for HS games.