Benjamin Hill at milb.com does a great and fun job of reviewing minor league parks. I always read his postings.
Recently, he posted about his favorite parks. Check out his reviews here:
Oddly, I have only been to two parks that he mentions (Durham Bulls Athletic Park and Modern Woodmen Park). I totally agree with him that these are two of the best. You cannot beat the view at Modern Woodmen at all.
Like Ben, I find it hard to rank the parks I go to. Plus, I always have a great time just being at a minor league ballgame!
Off the top of my head, I would say that my best game day experiences have been in Florence Kentucky, Indianapolis Indiana, Sevierville Tennessee, Lake County Ohio, Mahoning Valley Ohio, Pawtucket Rhode Island, Omaha Nebraska, New Britain Connecticut and Charleston West Virginia. I know I am leaving some great places out. I also know that I might come up with an entirely different list if you asked me to name my favorites tomorrow.